STATS 7 Lecture 5: StatsHWWk5
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Chapter 7, exercises 48, 58, 64, 88, 105, 106, 107, and 108. Chapter 8, exercises 60ab, 62, 68, 70ac, and 72bd. 7. 48) a. p(a)= 55%, p(a^c)= 45%, p(b|a)= 80% ,p(b|a^c)=10: p(a and b)= (0. 55)(0. 8)= 0. 44. About 44% of the voters are republican and voted for candidate x: p(a^c and b)= (0. 45)(0. 10)= 0. 045. About 4. 5% of the voters are non-republican and voted for candidate x: p(b)= 0. 045+0. 485= 0. 485, (0. 485)(100)= 48. 5% 7. 58) a. i think it is both reasonable and unreasonable because these are the traits that the witnesses observed from the robbery. However, the criminal could always stop smoking, dye his hair, or get another car/truck. It could be a flawed intuitive judgment about probability like confusion of the inverse, specific people vs. random individuals, or coincidences. Desktops (70%) sale (10%) (0. 3)(0. 05)+(0. 7)(0. 1)= 0. 015+0. 07= 0. 085= 8. 5% )= 0. 4/0. 7= 0. 571= 57. 1: p(a|not)= p(a and not)/p(not)= 0. 1/0. 3= 0. 333= 33. 3, 0. 571+0. 333= 0. 904= 90. 4% 8. 62) a. p(10(cid:1009)x(cid:1009)13)= (3)(0. 1)= 0. 3: p(x(cid:1009)5)= (5)(0. 1)= 0. 5, p(x(cid:1009)4)= (4)(0. 1)= 0. 4.
