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Unformatted text preview: Math 151 HW 2 Solutions Problems 4. Let A be the probability that at least on of a pair of dice lands on 6. Easy computaion gives: P ( A  i = 2) = 0, P ( A  i = 3) = 0, P ( A  i = 4) = 0, P ( A  i = 5) = 0, P ( A  i = 6) = 0, P ( A  i = 7) = 2 / 6, P ( A  i = 8) = 2 / 5, P ( A  i = 9) = 2 / 4, P ( A  i = 10) = 2 / 3, P ( A  i = 11) = 2 / 2, P ( A  i = 2) = 1 / 1. 18. Let E, I, L, C be the event that a person voted in the local election, is an independent, is a liberal, is a conservative, respectively. (a) Using Bayes Formula, P ( I  E ) = P ( IE ) P ( E ) = P ( I ) P ( E  I ) P ( I ) P ( E  I )+ P ( L ) P ( E  L )+ P ( C ) P ( E  C ) = (0 . 46)(0 . 35) (0 . 46)(0 . 35)+(0 . 30)(0 . 62)+(0 . 24)(0 . 58) = 0 . 331 Similar computation gives (b) 0.383 (c) 0.286 (d) (0 . 46)(0 . 35) + (0 . 30)(0 . 62) + (0 . 24)(0 . 58) = 0 . 4862, which means that 48.62 percent of voters participated. 26. Let C, M, W be event of being colorblind, man, woman, respectively. We want to calculate: P ( M  C ) = P ( MC ) P ( C ) = P ( M ) P ( C  M ) P ( M ) P ( C  M )+ P ( W ) P ( C  W ) Case1: (0 . 5)(0 . 05) (0 . 5)(0 . 05)+(0 . 5)(0 . 0025) = 0 . 95 Case2: (2 / 3)(0 . 05) (2 / 3)(0 . 05)+(1 / 3)(0 . 0025) = 0 . 98 32....
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This homework help was uploaded on 02/12/2008 for the course MATH 151 taught by Professor Liu during the Winter '08 term at Stanford.
 Winter '08
 Liu
 Probability

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