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UNIVERSIDADE FEDERAL DE GOIA´S INSTITUTO DE MATEMA´TICA E ESTATI´STICA GABARITO - LISTA 6 - PROBABILIDADE - VARIA´VEIS ALEATO´RIAS Curso: Estat´ıstica Disciplina: Estat´ıstica I Profa: Tatiane F. N. Melo 1. (a) {5} (b) {1,3,4,5,6,7,8,9,10} (c) {1,2,5,6,7,8,9,10} 2. Ω = {DD,NDD,DNNN,DNND,DNDN,DNDD,NNNN,NNND,NNDN, NNDD,NDNN,NDND} 3. (a) {abcd, abdc, acbd, acdb, adbc, adcb, bacd, badc, bcad, bcda, bdac, bdca, cabd, cadb, cbad, cbda, cdab, cdba, dabc, dacb, dbac, dbca, dcab} (b) A ∩B = {abcd, abdc} e A ∪B = {abcd, abdc, acbd, adbc, adcb, cbad, cbda, dbac, dbca} 4. Seja A: emperramento dos mancais, B: queima dos rolamentos e C: desgaste das escovas. Enta˜o P (A) = 8/13, P (B) = 4/13 e P (C) = 1/13. 5. (a) P (A¯ ∪ B¯) = 1− z (b) P (A¯ ∩B) = y − z (c) P (A¯ ∪B) = 1− x+ z (d) P (A¯ ∩ B¯) = 1− x− y + z 6. P (A ∪B ∪ C) = 5/8 7. Ω = {CC,CK,KC,KK}, com C: cara e K: coroa. 8. (a) Ω = {BBB,BBD,BDB,BDD,DBB,DBD,DDB,DDD} (b) A = {BDD,DBD,DDB} 9. (a) Ω = {t ∈ <; t ≥ 0} (b) A = {t ∈ <; 0 ≤ t < 20} 10. (a) P (B ∪D) = 13/18 (b) P (A¯ ∩ C¯) = 1/6 11. (a) 1/12 (b) 1/20 12. 4/45 13. (a) 5/8 (b) 7/8 (c) 3/4 14. 720 15. 455 16. P (X = 0) = 1/35, P (X = 1) = 12/35, P (X = 2) = 18/35, P (X = 3) = 4/35 17. E(X) = 1, 2 18. (a) P (Y = 0) = 1/16, P (Y = 1) = 4/16, P (Y = 2) = 6/16, P (Y = 3) = 4/16 e P (Y = 4) = 1/16 (b) E(Y ) = 2 e V ar(Y ) = 1 19. (a) E(X) = 3, 2 (b) V ar(X) = 0, 64 (c) P (X ≥ 2) = 0, 9728 (d) P (1 ≤ X < 3) = 0, 1792 20. E(V ) = 1− q e V ar(V ) = q(1− q) 21. (a) 0, 00038 (b) 0, 99957 22. (a) 0, 875348 (b) 0, 160623 23. (a) 0, 13252 (b) 0, 95581 24. 0, 00004 25. 0, 191154 26. (a) P (X = 0) = 0, 18, P (X = 1) = 0, 39, P (X = 2) = 0, 24, P (X = 3) = 0, 14, P (X = 4) = 0, 04 e P (X = 5) = 0, 01 (b) E(X) = 1, 5. (c) V ar(X) = 1, 25. 27. (a) Sim, pois ∑ P (xi) = 1 e 0 ≤ P (xi) ≤ 1, ∀i. (b) 0,25 (c) 0,35 (d) 0,40 (e) E(X) = 29, 25. (f) V ar(X) = 33, 1875. (g) 5,76 28. Temos para a varia´vel X: E(X) = 1, 841 e V ar(X) = 0, 786. Falta fazer para a varia´vel Y . 29. 0, 20 30. 31. 0,94295 32. 0,89065 33. 0,91044 34. 0,7938 35. (a) 0,02743 (b) 0,00006 (c) Como a populac¸a˜o original e´ normalmente distribu´ıda enta˜o a distribuic¸a˜o amostral das me´dias amostrais tambe´m e´ normal para qualquer tamanho amostral. 36. 37. 38. 39. (a) P (µ− σ ≤ X ≤ µ+ σ) = 0, 68268; (b) P (µ− 2σ ≤ X ≤ µ+ 2σ) = 0, 9545; (c) (d) (e) 40. (a) Z0 = 1, 645 41. (a) a me´dia e´ 60,5 kg e o desvio e´ 2 kg. (b) 0,6677 (c) 0,0030 (d) 0,0122 42. 0,2113
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