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Estatística 3
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Pergunta 1
0 em 1 pontos
This is correct. This is the only incorrect statement.
A 2015 CNN Money article provided the following information about the social class distribution of U.S. adults.
Apply probability rules in order to find the likelihood of an event
"multiple choice" question: select the correct answer.
What is the probability that a randomly chosen U.S. adults belongs to the Middle or Upper class?
Resposta Selecionada:
[Sem Resposta]
Resposta Correta:
.71
Pergunta 2
0 em 1 pontos
Skill: Determine the sampling distribution of the sample proportion and the sample mean in a given situation and apply it to determine likelihoods.
"multiple choice" question: select the correct answer.
20% of all the students at a large university are international students. Two random samples of students are chosen; a random sample of n=64 students and a random sample of n=400 students. In which of the two samples is it more likely that more than 25% of the sampled students are international students?
Resposta Selecionada:
[Sem Resposta]
Resposta Correta:
The sample of size n=64 since in there is more variability in the proportion of international students in smaller samples.
Pergunta 3
0 em 1 pontos
The probability table below summarizes the information that a large cable company provides about its customers:
Where:
T is the event that a randomly chosen customer subscribes to TV service
I is the event that a randomly chosen customer subscribes to Internet service
Create a probability table to organize and summarize information and use it to find probabilities
"multiple choice" question: select the correct answer.
In context, the fact that P(Not T and Not I) = 0 means that:
Resposta Selecionada:
[Sem Resposta]
Resposta Correta:
All the customers subscribe to at least one of the two services.
Pergunta 4
0 em 1 pontos
An epidemiological study investigated the prevalence of two contagious diseases ( Disease 1 and Disease 2) in the U.S.
Let A be the event that an individual contracts Disease 1
Let B be the event that an individual contracts Disease 2
Understand the reasoning behind the concept of conditional probability, calculate conditional probabilities and interpret them.
"multiple choice" question: select the correct answer.
What is the interpretation of P(B|A) in the context of this study?
Resposta Selecionada:
[Sem Resposta]
Resposta Correta:
(D) and (E) are both interpretations of P(B|A).
Pergunta 5
1 em 1 pontos
The weekly cost of maintenance and repairs for a company has a normal distribution with mean μ=$5500 and standard deviation σ=$400.
Note: For questions 19 and 20 you will need to use the Normal Table linked here
Find probabilities associated with the normal distribution.
"multiple choice" question: select the correct answer.
If $6200 is budgeted for the next week, what is the probability that the cost will exceed the budgeted amount?
Resposta Selecionada:
.0401
Resposta Correta:
.0401
Feedback da resposta:
This is correct.
P(X>6200)=[z=6200−5500400=1.75]=P(Z>1.75)=[table]=1−.9599=0401
Pergunta 6
0 em 1 pontos
The weekly cost of maintenance and repairs for a company has a normal distribution with mean μ=$5500 and standard deviation σ=$400.
Note: For questions 19 and 20 you will need to use the Normal Table linked here
Use the normal distribution as an approximation to the binomial distribution
"multiple choice" question: select the correct answer.
Which of the following is the correct justification for reliably using the normal approximation for X?
Resposta Selecionada:
[Sem Resposta]
Resposta Correta:
Both np = 1600 * 0.1 = 160 ≥ 10 and n(1 - p) = 1600 * 0.9 = 1440 ≥ 10
Pergunta 7
0 em 1 pontos
A lot of research is conducted on the sleeping habits of U.S. adults. One study reported that X, the amount of sleep per night of U.S. adults follows a normal distribution with mean μ=7.5 hours and standard deviation σ=1.2 hours.
Find probabilities associated with the normal distribution.
"multiple choice" question: select the correct answer.
Using the Standard Deviation Rule, 2.5% of U.S. adults sleep less than how many hours per night?
Resposta Selecionada:
[Sem Resposta]
Resposta Correta:
5.1
Pergunta 8
1 em 1 pontos
A patient with a failing heart is waiting for a heart transplant. If a suitable transplant is found, the patient’s chances of survival are much higher than the patient’s chances of survival if a suitable transplant is not found.
Let T be the event that a suitable Transplant is found.
Let S be the event that the patient Survives
The following probability tree summarizes the patient’s chances of finding a suitable transplant and survival.
Use the tree to answer the following questions:
Use Probability Trees as a tool to find probabilities
Use the general multiplication rule to find P(A and B)
"multiple choice" question: select the correct answer.
What is the probability that a suitable transplant is not found and the patient survives?
Resposta Selecionada:
.14
Resposta Correta:
.14
Feedback da resposta:
This is correct. P(not T and S)=P(not T)*P(S|not T)=.70*.20=.14
Pergunta 9
0 em 1 pontos
A family eats out twice a month – once during the first week of the month and once during the third week of the month, in one of the three local restaurants: R1, R2, or R3. Thus the outcome (R3, R2) denotes that on a given month the family eats in R3 during the first week of the month and in R2 during the third week of the month. It is possible for the family to eat at the same restaurant both on the first week and on the third week of the month.
Apply probability rules in order to find the likelihood of an event
"multiple choice" question: select the correct answer.
Let event A and event B be two disjoint events. Which of the following is incorrect?
Resposta Selecionada:
[Sem Resposta]
Resposta Correta:
Event A is the complement of Event B.
Pergunta 10
0 em 1 pontos
Airlines sometimes overbook flights. Suppose that for a plane with 111 seats an airline takes 115 reservations. Let the random variable X be the number of people who actually show up (out of the 115 who bought a ticket). From past experience the probability distribution of X is given in the following table:
x 108 109 110 111 112 113 114 115
P(X=x) 0.14 0.16 0.24 0.20 0.13 0.06 0.05 0.02
Resposta Selecionada:
[Sem Resposta]
Resposta Correta:
0.74
Pergunta 1
1 em 1 pontos
Skill: Determine the sampling distribution of the sample proportion and the sample mean in a given situation and apply it to determine likelihoods.
"multiple choice" question: select the correct answer.
20% of all the students at a large university are international students. Two random samples of students are chosen; a random sample of n=64 students and a random sample of n=400 students. In which of the two samples is it more likely that more than 25% of the sampled students are international students?
Resposta Selecionada:
The sample of size n=64 since in there is more variability in the proportion of international students in smaller samples.
Resposta Correta:
The sample of size n=64 since in there is more variability in the proportion of international students in smaller samples.
Feedback da resposta:
This is correct.
Pergunta 2
0 em 1 pontos
Fit thebinomial model when appropriate, and use it to perform probability calculations.
"multiple choice" question: select the correct answer.
The price of a European tour includes stopovers at five cities to be selected from 15 cities. In how many ways can a traveler plan such a tour if the traveler can only choose the five cities (the order is determined by the travel company).
Resposta Selecionada:
75
Resposta Correta:
3,003
Pergunta 3
0 em 1 pontos
The probability table below summarizes the information that a large cable company provides about its customers:
Where:
T is the event that a randomly chosen customer subscribes to TV service
I is the event that a randomly chosen customer subscribes to Internet service
Create a probability table to organize and summarize information and use it to find probabilities
"multiple choice" question: select the correct answer.
What is the probability that a randomly chosen customer subscribes to exactly one of the two services?
Resposta Selecionada:
[Sem Resposta]
Resposta Correta:
.15
Pergunta 4
1 em 1 pontos
Skill: Determine the sampling distribution of the sample proportion and the sample mean in a given situation and apply it to determine likelihoods.
"multiple choice" question: select the correct answer.
In which of the following scenarios we cannot safely assume that the sampling distribution of the sample mean X¯¯¯ is normal or approximately normal?
Resposta Selecionada:
The weight of the baggage checked by an individual passenger has mean μ=50pounds and standard deviation σ=15 pounds. A random sample of n=10 passengers is selected and the average weight of their checked baggage, x¯, is determined.
Resposta Correta:
The weight of the baggage checked by an individual passenger has mean μ=50pounds and standard deviation σ=15 pounds. A random sample of n=10 passengers is selected and the average weight of their checked baggage, x¯, is determined.
Feedback da resposta:
This is correct. We can assume that the sampling distribution of the sample mean is normal (or approximately normal) as long as at least one of the following two conditions holds:
• the variable of interest (weight in this case) is known to have a normal distribution in the population
• the sample size is large enough (n>30)
• In other words, the only case when we cannot assume that the sampling distribution of the sample mean is normal is when neither of the two conditions holds.In this case, we are not told that weights have anormal distribution and n=10<30.
Pergunta 5
1 em 1 pontos
A family eats out twice a month – once during the first week of the month and once during the third week of the month, in one of the three local restaurants: R1, R2, or R3. Thus the outcome (R3, R2) denotes that on a given month the family eats in R3 during the first week of the month and in R2 during the third week of the month. It is possible for the family to eat at the same restaurant both on the first week and on the third week of the month.
Apply probability rules in order to find the likelihood of an event
"multiple choice" question: select the correct answer.
Let B be the event that on a given month the family eats in R1 at least once.In context, the complement of event B, ‘Not B’ is the event that:
Resposta Selecionada:
in a given month, the family eats at R1 twice
Resposta Correta:
in a given month, the family eats at R1 twice
Feedback da resposta:
This is correct.
Pergunta 6
0 em 1 pontos
The weekly cost of maintenance and repairs for a company has a normal distribution with mean μ=$5500 and standard deviation σ=$400.
Note: For questions 19 and 20 you will need to use the Normal Table linked here
Find probabilities associated with the normal distribution.
"multiple choice" question: select the correct answer.
How much should be budgeted for weekly maintenance and repair so that there is only 1.5% chance that the cost will exceed the budgeted amount.
Resposta Selecionada:
5916
Resposta Correta:
6368
Pergunta 7
0 em 1 pontos
A family eats out twice a month – once during the first week of the month and once during the third week of the month, in one of the three local restaurants: R1, R2, or R3. Thus the outcome (R3, R2) denotes that on a given month the family eats in R3 during the first week of the month and in R2 during the third week of the month. It is possible for the family to eat at the same restaurant both on the first week and on the third week of the month.
Apply probability rules in order to find the likelihood of an event
Find the probability of events in the case when all outcomes are equally likely.
Determine the sample space of a random experiment and identify which outcomes are included in a particular event
"multiple choice" question: select the correct answer.
A fair four sided die with the numbers 1,2,3, and 4 is rolled twice. Thus, for example, the outcome (4, 1) denotes that the die landed on a 4 on the first roll and on 1 on the second. What is the probability that the sum of the numbers showing in the two rolls is 3?
Resposta Selecionada:
1/10
Resposta Correta:
1/8
Pergunta 8
1 em 1 pontos
The weekly cost of maintenance and repairs for a company has a normal distribution with mean μ=$5500 and standard deviation σ=$400.
Note: For questions 19 and 20 you will need to use the Normal Table linked here
Find probabilities associated with the normal distribution.
"multiple choice" question: select the correct answer.
If $6200 is budgeted for the next week, what is the probability that the cost will exceed the budgeted amount?
Resposta Selecionada:
.0401
Resposta Correta:
.0401
Feedback da resposta:
This is correct.
P(X>6200)=[z=6200−5500400=1.75]=P(Z>1.75)=[table]=1−.9599=0401
Pergunta 9
1 em 1 pontos
Airlines sometimes overbook flights. Suppose that for a plane with 111 seats an airline takes 115 reservations. Let the random variable X be the number of people who actually show up (out of the 115 who bought a ticket). From past experience the probability distribution of X is given in the following table:
x 108 109 110 111 112 113 114 115
P(X=x) 0.14 0.16 0.24 0.20 0.13 0.06 0.05 0.02
Find the probability distribution function of a discrete random variable and use it to find probabilities
"multiple choice" question: select the correct answer.
Given that an hour before the flight 109 passengers have already showed up to the flight, what is the probability that a total of 111 or less passengers will eventually show up to the flight? (Some answers are rounded to 2 decimal places).
Resposta Selecionada:
0.70
Resposta Correta:
0.70
Feedback da resposta:
This is correct.
Pergunta 10
0 em 1 pontos
Find the mean and variance of a linear transformation of a random variable, and the mean and variance of the sum of two independent random variables.
"multiple choice" question: select the correct answer.
Based on accumulated data, a propane gas company determined that the random variable X, the number of gallon required to fill a customer’s propane tank, has mean μx=300 gallons and standard deviation σx=40 gallons. The company charges the customer $25 service fee plus $2.50 per gallon of propone.
What is the mean and standard deviation of the amount that a customer is billed for?
Resposta Selecionada:
mean = $775, standard deviation = $125
Resposta Correta:
mean = $775, standard deviation = $100
Pergunta 1
1 em 1 pontosA family eats out twice a month – once during the first week of the month and once during the third week of the month, in one of the three local restaurants: R1, R2, or R3. Thus the outcome (R3, R2) denotes that on a given month the family eats in R3 during the first week of the month and in R2 during the third week of the month. It is possible for the family to eat at the same restaurant both on the first week and on the third week of the month.
Apply probability rules in order to find the likelihood of an event
"multiple choice" question: select the correct answer.
Let B be the event that on a given month the family eats in R1 at least once.In context, the complement of event B, ‘Not B’ is the event that:
Resposta Selecionada:
in a given month, the family eats at R1 twice
Resposta Correta:
in a given month, the family eats at R1 twice
Feedback da resposta:
This is correct.
Pergunta 2
1 em 1 pontos
Skill: Determine the sampling distribution of the sample proportion and the sample mean in a given situation and apply it to determine likelihoods.
"multiple choice" question: select the correct answer.
It was reported that 30% of all credit card users in the U.S. pay their card card bill in full every month.A random sample of size n=84 credit cards users is chosen. Which of the following is true regarding the effect of the increased sample size (from 21 to 84) on the mean and standard deviation of sampling distribution of pˆ?
Resposta Selecionada:
The mean of the sampling distribution will stay the same, but the standard deviation will increase.
Resposta Correta:
The mean of the sampling distribution will stay the same, but the standard deviation will increase.
Feedback da resposta:
This is correct.
Pergunta 3
0 em 1 pontos
A family eats out twice a month – once during the first week of the month and once during the third week of the month, in one of the three local restaurants: R1, R2, or R3. Thus the outcome (R3, R2) denotes that on a given month the family eats in R3 during the first week of the month and in R2 during the third week of the month. It is possible for the family to eat at the same restaurant both on the first week and on the third week of the month.
Determine the sample space of a random experiment and identify which outcomes are included in a particular event
"multiple choice" question: select the correct answer.
Which of the following is the correct sample space in this case?
Resposta Selecionada:
S= { (R1, R1) (R2, R2) (R3, R3) (R2, R1) (R3, R1) (R3, R2) }
Resposta Correta:
S= { (R1, R1) (R2, R2) (R3, R3) (R1, R2) (R2, R1) (R1, R3) (R3, R1) (R2, R3) (R3, R2) }
Pergunta 4
1 em 1 pontos
A patient with a failing heart is waiting for a heart transplant. If a suitable transplant is found, the patient’s chances of survival are much higher than the patient’s chances of survival if a suitable transplant is not found.
Let T be the event that a suitable Transplant is found.
Let S be the event that the patient Survives
The following probability tree summarizes the patient’s chances of finding a suitable transplant and survival.
Use the tree to answer the following questions:
Use Probability Trees as a tool to find probabilities
Use the general multiplication rule to find P(A and B)
"multiple choice" question: select the correct answer.
What is the probability that a suitable transplant is not found and the patient survives?
Resposta Selecionada:
.14
Resposta Correta:
.14
Feedback da resposta:
This is correct. P(not T and S)=P(not T)*P(S|not T)=.70*.20=.14
Pergunta 5
1 em 1 pontos
This is correct. This is the only incorrect statement.
A 2015 CNN Money article provided the following information about the social class distribution of U.S. adults.
Apply probability rules in order to find the likelihood of an event
"multiple choice" question: select the correct answer.
Two U.S. adults are chosen at random. What is the probability that both adults belong to the same social class?
Resposta Selecionada:
.29 * .29 + .50 * .50 + .21 * .21
Resposta Correta:
.29 * .29 + .50 * .50 + .21 * .21
Feedback da resposta:
This is correct. P(Both belong to the same social class) = P(Both Lower class or Both Middle class or Both Upper class) = [disjoint]P(Both Lower class) + P(Both Middle class) + P(Both Upper class) = [independence].29 * .29 + .50 * .50 + .21 * .21
Pergunta 6
1 em 1 pontos
Airlines sometimes overbook flights. Suppose that for a plane with 111 seats an airline takes 115 reservations. Let the random variable X be the number of people who actually show up (out of the 115 who bought a ticket). From past experience the probability distribution of X is given in the following table:
x 108 109 110 111 112 113 114 115
P(X=x) 0.14 0.16 0.24 0.20 0.13 0.06 0.05 0.02
Find the probability distribution function of a discrete random variable and use it to find probabilities
"multiple choice" question: select the correct answer.
Given that an hour before the flight 109 passengers have already showed up to the flight, what is the probability that a total of 111 or less passengers will eventually show up to the flight? (Some answers are rounded to 2 decimal places).
Resposta Selecionada:
0.70
Resposta Correta:
0.70
Feedback da resposta:
This is correct.
Pergunta 7
0 em 1 pontos
The National Survey on Drug and Health reported that 15% females in the age group of 12 to 20 years old are binge drinkers.
A random sample of 10 females from this age group is chosen, and let the random variable X be the number of females (out of 10) who are binge drinkers.
Fit the binomial model when appropriate, and use it to perform probability calculations.
"multiple choice" question: select the correct answer.
Which of the following is the correct probability distribution function of X?
Resposta Selecionada:
P(X=x)=0.15x x=0, 1, 2, 3...9, 10
Resposta Correta:
P(X=x)=10!x!(10−x)! ⋅ 0.15x ⋅ 0.8510−x x=0, 1, 2, 3...9, 10
Pergunta 8
1 em 1 pontos
Airlines sometimes overbook flights. Suppose that for a plane with 111 seats an airline takes 115 reservations. Let the random variable X be the number of people who actually show up (out of the 115 who bought a ticket). From past experience the probability distribution of X is given in the following table:
x 108 109 110 111 112 113 114 115
P(X=x) 0.14 0.16 0.24 0.20 0.13 0.06 0.05 0.02
Resposta Selecionada:
0.74
Resposta Correta:
0.74
Feedback da resposta:
This is correct. P(No more than 111 passenger show up) = P(X ≤ 111) = 0.14 + 0.16 + 0.24 + .20 = 0.74
Pergunta 9
0 em 1 pontos
The weekly cost of maintenance and repairs for a company has a normal distribution with mean μ=$5500 and standard deviation σ=$400.
Note: For questions 19 and 20 you will need to use the Normal Table linked here
Use the normal distribution as an approximation to the binomial distribution
"Fill in the blank" question: select the correct answer.
In this case, X can be approximated by a normal distribution with mean μ=
and standard deviation σ=
Resposta Selecionada:
0.9
Resposta Correta:
160
Pergunta 10
0 em 1 pontos
This is correct. This is the only incorrect statement.
A 2015 CNN Money article provided the following information about the social class distribution of U.S. adults.
Apply probability rules in order to find the likelihood of an event
"multiple choice" question: select the correct answer.
Four U.S.adults are selected at random. What is the probability that none of four belongs to the Upper Class?
Resposta Selecionada:
1 – .794
Resposta Correta:
.79 4
Pergunta 1
0 em 1 pontos
This is correct. This is the only incorrect statement.
A 2015 CNN Money article provided the following information about the social class distribution of U.S. adults.
Apply probability rules in order to find the likelihood of an event
"multiple choice" question: select the correct answer.
Two U.S. adults are chosen at random.
Which of the following is the probability that first chosen is Middle Class and the second chosen is Lower Class? In other words, which of the following is P(A and B), where events A and B are as defined in Question #8.
Resposta Selecionada:
.50*.50 + .29*.29
Resposta Correta:
.50 * .29
Pergunta 2
0 em 1 pontos
Skill: Determine the sampling distribution of the sample proportion and the sample mean in a given situation and apply it to determine likelihoods.
"multiple choice" question: select the correct answer.
A random sample of 21 credit card users is chosen.What is the mean and standard deviation of pˆ, the sample proportion of credit card users who pay their bill in full every month? (some answers are rounded).
Resposta Selecionada:
Mean = 0.21, standard deviation = 0.1
Resposta Correta:
Mean = 0.30, standard deviation = 0.1
Pergunta 3
0 em 1 pontos
A patient with a failing heart is waiting for a heart transplant. If a suitable transplant is found, the patient’s chances of survival are much higher than the patient’s chances of survival if a suitable transplant is not found.
Let T be the event that a suitable Transplant is found.
Let S be the event that the patient Survives
The following probability tree summarizes the patient’s chances of finding a suitable transplant and survival.
Use the tree to answer the following questions:
Use Probability Trees as a tool to find probabilities
Use the general multiplication rule to find P(A and B)
"multiple choice" question: select the correct answer.
What is the probability that a suitable transplant is found and the patient survives?
Resposta Selecionada:
.14
Resposta Correta:
.225
Pergunta 4
0 em 1 pontos
Fit the binomial model when appropriate, and use it to perform probability calculations.
"multiple choice" question: select the correct answer.
What are the mean and standard deviation of X, the number of females out of the 10 chosen who are binge drinkers?
Resposta Selecionada:
μx=10(0.15)−−−−−−−√ , σx=10(0.15)(0.85)−−−−−−−−−−−−√
Resposta Correta:
μx=10(0.15) , σx=10(0.15)(0.85)−−−−−−−−−−−−√
Pergunta 5
0 em 1 pontos
Skill: Distinguish between a parameter and a statistic and recognize the concept of sampling variability.
"multiple choice" question: select the correct answer.
Which of the following statements is consistent with the idea of sampling variability?
Resposta Selecionada:
[Sem Resposta]
Resposta Correta:
If we were to select a different random sample of 625 newborns, we can expect the mean and standard deviation in this sample to be different than the mean and the standard deviation in the first sample.
Pergunta 6
1 em 1 pontos
A patient with a failing heart is waiting for a heart transplant. If a suitable transplant is found, the patient’s chances of survival are much higher than the patient’s chances of survival if a suitable transplant is not found.
Let T be the event that a suitable Transplant is found.
Let S be the event that the patient Survives
The following probability tree summarizes the patient’s chances of finding a suitable transplant and survival.
Use the tree to answer the following questions:
Use Probability Trees as a tool to find probabilities
Use the general multiplication rule to find P(A and B)
"multiple choice" question: select the correct answer.
What is the probability that a suitable transplant is not found and the patient survives?
Resposta Selecionada:
.14
Resposta Correta:
.14
Feedback da resposta:
This is correct. P(not T and S)=P(not T)*P(S|not T)=.70*.20=.14
Pergunta 7
0 em 1 pontos
Airlines sometimes overbook flights. Suppose that for a plane with 111 seats an airline takes 115 reservations. Let the random variable X be the number of people who actually show up (out of the 115 who bought a ticket). From past experience the probability distribution of X is given in the following table:
x 108 109 110 111 112 113 114 115
P(X=x) 0.14 0.16 0.24 0.20 0.13 0.06 0.05 0.02
Find the probability distribution function of a discrete random variable and use it to find probabilities
"multiple choice" question: select the correct answer.
Which of the following is the correct way to calculate the probability that at least 109 passengers show up to the flight?
Resposta Selecionada:
0.24 + 0.20 + 0.13 + 0.06 + 0.05 + 0.02
Resposta Correta:
Both (0.16 + 0.24 + 0.20 + 0.13 + 0.06 + 0.05 + 0.02) and (1 – 0.14) are correct.
Pergunta 8
1 em 1 pontos
Understand the concept of a random variable and distinguish between discrete and continuous random variables
"multiple choice" question: select the correct answer.
Which of the following is a continuous random variable?
Resposta Selecionada:
The exact time an individual spends on the Internet every day.
Resposta Correta:
The exact time an individual spends on the Internet every day.
Feedback da resposta:
This is correct.
Pergunta 9
0 em 1 pontos
Understand how relative frequency can be used to estimate the probability of an event and apply this approach in practice.
"multiple choice" question: select the correct answer.
1250 randomly chosen individuals from a certain population are tested for the presence of the HIV virus, and 20 are found to be carriers of the virus. Based on this information, what is the estimate of P(V), the probability that a randomly chosen person from this population carries the HIV virus?
Resposta Selecionada:
[Sem Resposta]
Resposta Correta:
.016
Pergunta 10
0 em 1 pontos
Understand how probability quantifies uncertainty and relate the probability of an event to the likelihood of the event occurring.
"multiple choice" question: select the correct answer.
Which of the following is true regarding a probability of an event P(A)?
Resposta Selecionada:
P(A)≥0
Resposta Correta:
0≤P(A)≤1
Pergunta 1
0 em 1 pontos
A lot of research is conducted on the sleeping habits of U.S. adults. One study reported that X, the amount of sleep per night of U.S. adults follows a normal distribution with mean μ=7.5 hours and standard deviation σ=1.2 hours.
Skill:
Find probabilities associated with the normal distribution.
"multiple choice" question: select the correct answer.
Which of the following is the correct interpretation of the fact that the value x has a Z-score of 0.25
Resposta Selecionada:
There is 25% chance of getting a value smaller than x.
Resposta Correta:
x is .25 standard deviations above the mean.
Pergunta 2
1 em 1 pontos
Find the mean and variance of a linear transformation of a random variable, and the mean and variance of the sum of two independent random variables.
"multiple choice" question: select the correct answer.
Based on accumulated data, a propane gas company determined that the randomvariable X, the number of gallon required to fill a customer’s propane tank, has mean μx=300 gallons and standard deviation σx=40 gallons. The company charges the customer $25 service fee plus $2.50 per gallon of propone.
What is the mean and standard deviation of the amount that a customer is billed for?
Resposta Selecionada:
mean = $775, standard deviation = $100
Resposta Correta:
mean = $775, standard deviation = $100
Feedback da resposta:
This is correct.
Pergunta 3
1 em 1 pontos
A family eats out twice a month – once during the first week of the month and once during the third week of the month, in one of the three local restaurants: R1, R2, or R3. Thus the outcome (R3, R2) denotes that on a given month the family eats in R3 during the first week of the month and in R2 during the third week of the month. It is possible for the family to eat at the same restaurant both on the first week and on the third week of the month.
Apply probability rules in order to find the likelihood of an event
Find the probability of events in the case when all outcomes are equally likely.
Determine the sample space of a random experiment and identify which outcomes are included in a particular event
"multiple choice" question: select the correct answer.
A fair four sided die with the numbers 1,2,3, and 4 is rolled twice. Thus, for example, the outcome (4, 1) denotes that the die landed on a 4 on the first roll and on 1 on the second. What is the probability that the sum of the numbers showing in the two rolls is 3?
Resposta Selecionada:
1/8
Resposta Correta:
1/8
Feedback da resposta:
This is correct. This experiment has 16 possible outcomes:(1,1) (1,2) (1,3) (1,4)(2,1) (2,2) (2,4) (2,4)(3,1) (3,2) (3,3) (3,4)(4,1) (4,2) (4,3) (4,4)and since the die is fair, all 16 outcomes are equally likely. In two of the 16 possible outcomes the sum of the numbers is 3 [(1,2) and (2,1)] and therefore the probability is 2/16=1/8.
Pergunta 4
1 em 1 pontos
A patient with a failing heart is waiting for a heart transplant. If a suitable transplant is found, the patient’s chances of survival are much higher than the patient’s chances of survival if a suitable transplant is not found.
Let T be the event that a suitable Transplant is found.
Let S be the event that the patient Survives
The following probability tree summarizes the patient’s chances of finding a suitable transplant and survival.
Use the tree to answer the following questions:
Use Probability Trees as a tool to find probabilities
Use the general multiplication rule to find P(A and B)
"multiple choice" question: select the correct answer.
What is the probability that a suitable transplant is not found and the patient survives?
Resposta Selecionada:
.14
Resposta Correta:
.14
Feedback da resposta:
This is correct. P(not T and S)=P(not T)*P(S|not T)=.70*.20=.14
Pergunta 5
1 em 1 pontos
This is correct. This is the only incorrect statement.
A 2015 CNN Money article provided the following information about the social class distribution of U.S. adults.
Apply probability rules in order to find the likelihood of an event
"Fill in the blank" question: select the correct answer.
Two U.S. adults are chosen at random.Let A be the event that the first adult belongs to the Middle ClassLet B be the event that the second adult belongs to the Lower class.
Complete the following sentences:
Events A and B are
.Events A and B are
Resposta Selecionada:
Independent
Resposta Correta:
Independent
Feedback da resposta:
This is correct. Since the two chosen are from a large population (of all U.S. adults), the social class of the first adults has no effect on the social class of the second chosen adult.
Pergunta 6
0 em 1 pontos
Understand how probability quantifies uncertainty and relate the probability of an event to the likelihood of the event occurring.
"multiple choice" question: select the correct answer.
Which of the following represents the probability of an event that is more likely not to occur than it is to occur, but would not be unusual for it to occur?
Resposta Selecionada:
0.999
Resposta Correta:
0.32
Pergunta 7
1 em 1 pontos
Airlines sometimes overbook flights. Suppose that for a plane with 111 seats an airline takes 115 reservations. Let the random variable X be the number of people who actually show up (out of the 115 who bought a ticket). From past experience the probability distribution of X is given in the following table:
x 108 109 110 111 112 113 114 115
P(X=x) 0.14 0.16 0.24 0.20 0.13 0.06 0.05 0.02
Find the probability distribution function of a discrete random variable and use it to find probabilities
"multiple choice" question: select the correct answer.
Which of the following is the correct way to calculate the probability that at least 109 passengers show up to the flight?
Resposta Selecionada:
Both (0.16 + 0.24 + 0.20 + 0.13 + 0.06 + 0.05 + 0.02) and (1 – 0.14) are correct.
Resposta Correta:
Both (0.16 + 0.24 + 0.20 + 0.13 + 0.06 + 0.05 + 0.02) and (1 – 0.14) are correct.
Feedback da resposta:
This is correct.
Pergunta 8
1 em 1 pontos
Fit the binomial model when appropriate, and use it to perform probability calculations.
"multiple choice" question: select the correct answer.
What are the mean and standard deviation of X, the number of females out of the 10 chosen who are binge drinkers?
Resposta Selecionada:
μx=10(0.15) , σx=10(0.15)(0.85)−−−−−−−−−−−−√
Resposta Correta:
μx=10(0.15) , σx=10(0.15)(0.85)−−−−−−−−−−−−√
Feedback da resposta:
This is correct.
Pergunta 9
0 em 1 pontos
A family eats out twice a month – once during the first week of the month and once during the third week of the month, in one of the three local restaurants: R1, R2, or R3. Thus the outcome (R3, R2) denotes that on a given month the family eats in R3 during the first week of the month and in R2 during the third week of the month. It is possible for the family to eat at the same restaurant both on the first week and on the third week of the month.
Determine the sample space of a random experiment and identify which outcomes are included in a particular event
"multiple choice" question: select the correct answer.
Let A be the event that on a given month the family eats in R2 exactly once. What are the possible outcomes for this event?
Resposta Selecionada:
{ (R1, R1) (R3, R3) (R1, R2) (R2, R1) (R1, R3) (R3, R1) (R2, R3) (R3, R2) }
Resposta Correta:
{ (R1, R2) (R2, R1) (R2, R3) (R3, R2) }
Pergunta 10
0 em 1 pontos
Understand how probability quantifies uncertainty and relate the probability of an event to the likelihood of the event occurring.
"multiple choice" question: select the correct answer.
Which of the following is true regarding a probability of an event P(A)?
Resposta Selecionada:
0<P(A)<1
Resposta Correta:
0≤P(A)≤1
Pergunta 1
1 em 1 pontos
A patient with a failing heart is waiting for a heart transplant. If a suitable transplant is found, the patient’s chances of survival are much higher than the patient’s chances of survival if a suitable transplant is not found.
Let T be the event that a suitable Transplant is found.
Let S be the event that the patient Survives
The following probability tree summarizes the patient’s chances of finding a suitable transplant and survival.
Use the tree to answer the following questions:
Use Probability Trees as a tool to find probabilities
"multiplechoice" question: select the correct answer.
Given that the patient survives, what is the probability that a suitable transplant was found (what is P(T|S))? (Some answers were rounded).
Resposta Selecionada:
.616
Resposta Correta:
.616
Feedback da resposta:
This is correct.
P(T│S)=.30×.75.30×.75 + .70*.20=.225.365≈.616
Pergunta 2
1 em 1 pontos
The mammogram is the most common screening test for breast cancer. Its purpose is to detect breast cancer early when it is easier to treat.
A positive mammogram test results indicates that signs of possible cancer were found.
A negative mammogram test rests indicates that no signs of cancer were found.
Like any other medical test, the mammogram test is not “perfect”.
The following information is available:
· 1% of women over 50 have breast cancer.
· Given that a woman over 50 has breast cancer, there 90% chance that the mammogram test will be positive (i.e., detect the cancer)
· Given that a woman over 50 does not have cancer, there is 8% chance that the mammogram test will be positive (by mistake).
Let C be the event that a woman over 50 has breast cancer
Let M be the event that the mammogram test will be positive.
Understand the reasoning behind the concept of conditional probability, calculate conditional probabilities and interpret them.
"multiple choice" question: select the correct answer.
The problem gives you three pieces of information (probabilities). Which of the following probabilities is not given in the problem?
Resposta Selecionada:
P(C and M)
Resposta Correta:
P(C and M)
Feedback da resposta:
This is correct.
Pergunta 3
1 em 1 pontos
A lot of research is conducted on the sleeping habits of U.S. adults. One study reported that X, the amount of sleep per night of U.S. adults follows a normal distribution with mean μ=7.5 hours and standard deviation σ=1.2 hours.
Skill:
Find probabilities associated with the normal distribution.
"multiple choice" question: select the correct answer.
Which of the following is the correct interpretation of the fact that the value x has a Z-score of 0.25
Resposta Selecionada:
x is .25 standard deviations above the mean.
Resposta Correta:
x is .25 standard deviations above the mean.
Feedback da resposta:
This is correct.
Pergunta 4
0 em 1 pontos
An epidemiological study investigated the prevalence of two contagious diseases ( Disease 1 and Disease 2) in the U.S.
Let A be the event that an individual contracts Disease 1
Let B be the event that an individual contracts Disease 2
Understand the reasoning behind the concept of conditional probability, calculate conditional probabilities and interpret them.
"multiple choice" question: select the correct answer.
Recall that the epidemiological study reported the following:
· There is 15% chance of contracting Disease 1
· There is 10% chance of contracting Disease 2
· There is 3% chance of contracting both Disease 1 and Disease 2
If an individual contracts Disease 2, what is the probability that he/she will contract Disease 1?
Resposta Selecionada:
.03
Resposta Correta:
.03/.10 = .30
Pergunta 5
1 em 1 pontos
Fit the binomial model when appropriate, and use it to perform probability calculations.
"multiple choice" question: select the correct answer.
The price of a European tour includes stopovers at five cities to be selected from 15 cities. In how many ways can a traveler plan such a tour if the traveler can only choose the five cities (the order is determined by the travel company).
Resposta Selecionada:
3,003
Resposta Correta:
3,003
Feedback da resposta:
This is correct.
Pergunta 6
0 em 1 pontos
A large cable company provides the following information regarding its customers:
· 50% of all customers subscribe to internet service.
· If a customer is an internet subscriber, there is 64% chance that he/she is also a phone subscriber.
· If a customer is a phone subscriber, there is 80% chance that he/she is also an internet subscriber.
Let A be the event that a customer subscribes to internet service
Let B be the event that a customer subscribes to phone service
Determine whether two events are independent
"multiple choice" question: select the correct answer.
Are the two subscriptions (phone, Internet) independent of each other?
Resposta Selecionada:
No, since P(A|B) = .80 is not equal to P(B|A) = .64
Resposta Correta:
No, since P(A)=.50 is not equal to P(A|B) = .80
Pergunta 7
1 em 1 pontos
A lot of research is conducted on the sleeping habits of U.S. adults. One study reported that X, the amount of sleep per night of U.S. adults follows a normal distribution with mean μ=7.5 hours and standard deviation σ=1.2 hours.
Find probabilities associated with the normal distribution.
"multiple choice" question: select the correct answer.
Using the Standard Deviation Rule, 2.5% of U.S. adults sleep less than how many hours per night?
Resposta Selecionada:
5.1
Resposta Correta:
5.1
Feedback da resposta:
This is correct. By the Standard deviation Rule 95% of U.S. adults sleep between 7.5 – 2(1.2) = 5.1 hours and 7.5 + 2(1.2)=9.9 hours. Therefore, 2.5% of U.S. adults sleep less than 5.1 hours.
Pergunta 8
1 em 1 pontos
Find the mean and variance of a linear transformation of a random variable, and the mean and variance of the sum of two independent random variables.
"multiple choice" question: select the correct answer.
Based on accumulated data, a propane gas company determined that the random variable X, the number of gallon required to fill a customer’s propane tank, has mean μx=300 gallons and standard deviation σx=40 gallons. The company charges the customer $25 service fee plus $2.50 per gallon of propone.
What is the mean and standard deviation of the amount that a customer is billed for?
Resposta Selecionada:
mean = $775, standard deviation = $100
Resposta Correta:
mean = $775, standard deviation = $100
Feedback da resposta:
This is correct.
Pergunta 9
0 em 1 pontos
Skill: Determine the sampling distribution of the sample proportion and the sample mean in a given situation and apply it to determine likelihoods.
"multiple choice" question: select the correct answer. Suppose that the average number of defects in the sample of n=225cars was found to be x̅=5.1. What is the z-score of this average?
Resposta Selecionada:
-3
Resposta Correta:
3
Pergunta 10
0 em 1 pontos
Skill: Determine the sampling distribution of the sample proportion and the sample mean in a given situation and apply it to determine likelihoods.
"multiple choice" question: select the correct answer.
There is 95% chance in a random sample of n=84 card users, the proportion of those who pay their bills in full every month will be:
Resposta Selecionada:
We cannot answer this question since for n=84 we cannot safely assume that the sampling distribution is normal.
Resposta Correta:
Between .20 and .40
Pergunta 1
0 em 1 pontos
A family eats out twice a month – once during the first week of the month and once during the third week of the month, in one of the three local restaurants: R1, R2, or R3. Thus the outcome (R3, R2) denotes that on a given month the family eats in R3 during the first week of the month and in R2 during the third week of the month. It is possible for the family to eat at the same restaurant both on the first week and on the thirdweek of the month.
Find the probability of events in the case when all outcomes are equally likely.
"multiple choice" question: select the correct answer.
Assume that each time that the family goes out to eat they choose one of the three restaurants at random, and again, let A be the event that on a given the family eats in R2 exactly once. What is P(A)?
Resposta Selecionada:
1/9
Resposta Correta:
4/9
Pergunta 2
1 em 1 pontos
The probability table below summarizes the information that a large cable company provides about its customers:
Where:
T is the event that a randomly chosen customer subscribes to TV service
I is the event that a randomly chosen customer subscribes to Internet service
Create a probability table to organize and summarize information and use it to find probabilities
"multiple choice" question: select the correct answer.
What is the correct representation and probability of the event that a customer subscribes only to TV service?
Resposta Selecionada:
P(T and Not I) = .05
Resposta Correta:
P(T and Not I) = .05
Feedback da resposta:
This is correct.
Pergunta 3
1 em 1 pontos
Skill: Determine the sampling distribution of the sample proportion and the sample mean in a given situation and apply it to determine likelihoods.
"multiple choice" question: select the correct answer.
20% of all the students at a large university are international students. Two random samples of students are chosen; a random sample of n=64 students and a random sample of n=400 students. In which of the two samples is it more likely that more than 25% of the sampled students are international students?
Resposta Selecionada:
The sample of size n=64 since in there is more variability in the proportion of international students in smaller samples.
Resposta Correta:
The sample of size n=64 since in there is more variability in the proportion of international students in smaller samples.
Feedback da resposta:
This is correct.
Pergunta 4
0 em 1 pontos
An epidemiological study investigated the prevalence of two contagious diseases ( Disease 1 and Disease 2) in the U.S.
Let A be the event that an individual contracts Disease 1
Let B be the event that an individual contracts Disease 2
Determine whether two events are independent
"multiple choice" question: select the correct answer.
Recall that the epidemiological study reported the following:
· There is 15% chance of contracting Disease 1 (Event A)
· There is 10% chance of contracting Disease 2 (Event B)
· There is 3% chance of contracting both Disease 1 and Disease 2
Are the two diseases being contracted independently of each other (are events A, B independent)?
Resposta Selecionada:
No, since P(A and B)=.03 is not equal to P(A)=.15
Resposta Correta:
No, since P(A and B)=.03 is not equal to P(A)*P(B)=.15*.10=.015
Pergunta 5
0 em 1 pontos
A patient with a failing heart is waiting for a heart transplant. If a suitable transplant is found, the patient’s chances of survival are much higher than the patient’s chances of survival if a suitable transplant is not found.
Let T be the event that a suitable Transplant is found.
Let S be the event that the patient Survives
The following probability tree summarizes the patient’s chances of finding a suitable transplant and survival.
Use the tree to answer the following questions:
Use Probability Trees as a tool to find probabilities
"multiple choice" question: select the correct answer.
What is the probability that the patient survives? (what is P(S)?)
Resposta Selecionada:
.225
Resposta Correta:
.365
Pergunta 6
1 em 1 pontos
The following three probability histograms represent the probability distributions of the random variables X, Y, and W.
As is evident from the probability histograms, the mean of all three random variables is 5.
Find the mean and variance of a discrete random variable, and apply these concepts for solving real world problems.
"multiple choice" question: select the correct answer.
Which of the three random variables has the largest standard deviation?
Resposta Selecionada:
X
Resposta Correta:
X
Feedback da resposta:
This is correct.
Pergunta 7
1 em 1 pontos
Find the probability distribution function of a discrete random variable and use it to find probabilities
"multiple choice" question: select the correct answer.
Resposta Selecionada:
0.7
Resposta Correta:
0.7
Feedback da resposta:
This is correct. P(X >2) = P(X=3) + P(X=4) = 6/20 + 8/20 = 14/20 = 0.7
Pergunta 8
1 em 1 pontos
Airlines sometimes overbook flights. Suppose that for a plane with 111 seats an airline takes 115 reservations. Let the random variable X be the number of people who actually show up (out of the 115 who bought a ticket). From past experience the probability distribution of X is given in the following table:
x 108 109 110 111 112 113 114 115
P(X=x) 0.14 0.16 0.24 0.20 0.13 0.06 0.05 0.02
Find the probability distribution function of a discrete random variable and use it to find probabilities
"multiple choice" question: select the correct answer.
Which of the following is the correct way to calculate the probability that at least 109 passengers show up to the flight?
Resposta Selecionada:
Both (0.16 + 0.24 + 0.20 + 0.13 + 0.06 + 0.05 + 0.02) and (1 – 0.14) are correct.
Resposta Correta:
Both (0.16 + 0.24 + 0.20 + 0.13 + 0.06 + 0.05 + 0.02) and (1 – 0.14) are correct.
Feedback da resposta:
This is correct.
Pergunta 9
0 em 1 pontos
Understand how probability quantifies uncertainty and relate the probability of an event to the likelihood of the event occurring.
"multiple choice" question: select the correct answer.
Which of the following is true regarding a probability of an event P(A)?
Resposta Selecionada:
0<P(A)<1
Resposta Correta:
0≤P(A)≤1
Pergunta 10
1 em 1 pontos
Airlines sometimes overbook flights. Suppose that for a plane with 111 seats an airline takes 115 reservations. Let the random variable X be the number of people who actually show up (out of the 115 who bought a ticket). From past experience the probability distribution of X is given in the following table:
x 108 109 110 111 112 113 114 115
P(X=x) 0.14 0.16 0.24 0.20 0.13 0.06 0.05 0.02
Find the probability distribution function of a discrete random variable and use it to find probabilities
"multiple choice" question: select the correct answer.
Given that an hour before the flight 109 passengers have already showed up to the flight, what is the probability that a total of 111 or less passengers will eventually show up to the flight? (Some answers are rounded to 2 decimal places).
Resposta Selecionada:
0.70
Resposta Correta:
0.70
Feedback da resposta:
This is correct.
Pergunta 1
1 em 1 pontos
This is correct. This is the only incorrect statement.
A 2015 CNN Money article provided the following information about the social class distribution of U.S. adults.
Apply probability rules in order to find the likelihood of an event
"multiple choice" question: select the correct answer.
Two U.S. adults are chosen at random.
Which of the following is the probability that first chosen is Middle Class and the second chosen is Lower Class? In other words, which of the following is P(A and B), where events A and B are as defined in Question #8.
Resposta Selecionada:.50 * .29
Resposta Correta:
.50 * .29
Feedback da resposta:
This is correct. P(A and B) = [A, B independent] = P(A) * P(B) = .50 * .29
Pergunta 2
1 em 1 pontos
A patient with a failing heart is waiting for a heart transplant. If a suitable transplant is found, the patient’s chances of survival are much higher than the patient’s chances of survival if a suitable transplant is not found.
Let T be the event that a suitable Transplant is found.
Let S be the event that the patient Survives
The following probability tree summarizes the patient’s chances of finding a suitable transplant and survival.
Use the tree to answer the following questions:
Use Probability Trees as a tool to find probabilities
Use the general multiplication rule to find P(A and B)
"multiple choice" question: select the correct answer.
What is the probability that a suitable transplant is not found and the patient survives?
Resposta Selecionada:
.14
Resposta Correta:
.14
Feedback da resposta:
This is correct. P(not T and S)=P(not T)*P(S|not T)=.70*.20=.14
Pergunta 3
1 em 1 pontos
A family eats out twice a month – once during the first week of the month and once during the third week of the month, in one of the three local restaurants: R1, R2, or R3. Thus the outcome (R3, R2) denotes that on a given month the family eats in R3 during the first week of the month and in R2 during the third week of the month. It is possible for the family to eat at the same restaurant both on the first week and on the third week of the month.
Find the probability of events in the case when all outcomes are equally likely.
"multiple choice" question: select the correct answer.
Assume that each time that the family goes out to eat they choose one of the three restaurants at random, and again, let A be the event that on a given the family eats in R2 exactly once. What is P(A)?
Resposta Selecionada:
4/9
Resposta Correta:
4/9
Feedback da resposta:
This is correct.
Pergunta 4
1 em 1 pontos
Find the probability distribution function of a discrete random variable and use it to find probabilities
"multiple choice" question: select the correct answer.
Resposta Selecionada:
0.7
Resposta Correta:
0.7
Feedback da resposta:
This is correct. P(X >2) = P(X=3) + P(X=4) = 6/20 + 8/20 = 14/20 = 0.7
Pergunta 5
0 em 1 pontos
A large cable company provides the following information regarding its customers:
· 50% of all customers subscribe to internet service.
· If a customer is an internet subscriber, there is 64% chance that he/she is also a phone subscriber.
· If a customer is a phone subscriber, there is 80% chance that he/she is also an internet subscriber.
Let A be the event that a customer subscribes to internet service
Let B be the event that a customer subscribes to phone service
Use the general multiplication rule to find P(A and B)
"multiple choice" question: select the correct answer.
What is the probability that a customer subscribes to both internet and phone service?
Resposta Selecionada:
P(A) * P(B), but since we do not know P(B), there not enough information to answer this question.
Resposta Correta:
P(A) * P(B|A) = .50 * .64 = .32
Pergunta 6
1 em 1 pontos
A lot of research is conducted on the sleeping habits of U.S. adults. One study reported that X, the amount of sleep per night of U.S. adults follows a normal distribution with mean μ=7.5 hours and standard deviation σ=1.2 hours.
Find probabilities associated with the normal distribution.
"multiple choice" question: select the correct answer.
Using the Standard Deviation Rule, 2.5% of U.S. adults sleep less than how many hours per night?
Resposta Selecionada:
5.1
Resposta Correta:
5.1
Feedback da resposta:
This is correct. By the Standard deviation Rule 95% of U.S. adults sleep between 7.5 – 2(1.2) = 5.1 hours and 7.5 + 2(1.2)=9.9 hours. Therefore, 2.5% of U.S. adults sleep less than 5.1 hours.
Pergunta 7
1 em 1 pontos
Fit the binomial model when appropriate, and use it to perform probability calculations.
"multiple choice" question: select the correct answer.
The price of a European tour includes stopovers at five cities to be selected from 15 cities. In how many ways can a traveler plan such a tour if the traveler can only choose the five cities (the order is determined by the travel company).
Resposta Selecionada:
3,003
Resposta Correta:
3,003
Feedback da resposta:
This is correct.
Pergunta 8
1 em 1 pontos
Airlines sometimes overbook flights. Suppose that for a plane with 111 seats an airline takes 115 reservations. Let the random variable X be the number of people who actually show up (out of the 115 who bought a ticket). From past experience the probability distribution of X is given in the following table:
x 108 109 110 111 112 113 114 115
P(X=x) 0.14 0.16 0.24 0.20 0.13 0.06 0.05 0.02
Resposta Selecionada:
0.74
Resposta Correta:
0.74
Feedback da resposta:
This is correct. P(No more than 111 passenger show up) = P(X ≤ 111) = 0.14 + 0.16 + 0.24 + .20 = 0.74
Pergunta 9
1 em 1 pontos
A patient with a failing heart is waiting for a heart transplant. If a suitable transplant is found, the patient’s chances of survival are much higher than the patient’s chances of survival if a suitable transplant is not found.
Let T be the event that a suitable Transplant is found.
Let S be the event that the patient Survives
The following probability tree summarizes the patient’s chances of finding a suitable transplant and survival.
Use the tree to answer the following questions:
Use Probability Trees as a tool to find probabilities
"multiple choice" question: select the correct answer.
Given that the patient survives, what is the probability that a suitable transplant was found (what is P(T|S))? (Some answers were rounded).
Resposta Selecionada:
.616
Resposta Correta:
.616
Feedback da resposta:
This is correct.
P(T│S)=.30×.75.30×.75 + .70*.20=.225.365≈.616
Pergunta 10
0 em 1 pontos
Fit the binomial model when appropriate, and use it to perform probability calculations.
"multiple choice" question: select the correct answer.
The National Survey on Drug Use and Health also reported that 21% of males in the same age group (12-20) are binge drinkers.
Suppose that in addition to the 10 randomly chosen females, a random sample 10 males from the same age group is chosen (to a total of 20).
Let the random variable Y be the total number of males and females (out of 20) who are binge drinkers.
Which of the following is true regarding the random variable Y?
Resposta Selecionada:
Y does not have a binomial distribution since the number of trials n is not fixed.
Resposta Correta:
Y has a binomial distribution with n=20 and p=.18
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