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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=

160
Resposta Correta:

160
Feedback da resposta:
This is correct. The mean of the normal approximation is the mean of the binomial distribution which is np=1600*0.1=160.
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?

0.14 + 0.16
Resposta Correta:

Both (0.16 + 0.24 + 0.20 + 0.13 + 0.06 + 0.05 + 0.02) and (1 – 0.14) are correct.
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?

The weight of the baggage checked by an individual passenger has a normal distribution with 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.
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.
Understand how a density function is used to find probabilities involving continuous random variables.
"multiple choice" question: select the correct answer.
The shaded area in the image below represents which of the following probabilities?   