Exam1_practice_solutions

# Exam1_practice_solutions - 5E practice problems for exam 1...

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Unformatted text preview: 5E practice problems for exam 1 1. (a) 212 + 36 = 248 out of the 500 husbands earn less than \$75 , 000. So 248 500 = . 496. (b) Out of the 252 couples that have husbands with income over \$75 , 000, 54 of the wives also earned more than that amount. So the probability is 54 252 = . 214. We could also think of this as P ( W | H ) = P ( H &amp;amp; W ) P ( H ) = 54 / 500 248 / 500 = . 214, where H is the event that the husband earns over 75, and W is the event that the wife does. 2. If A is the event that Bill will drive the Honda, and B is is the event that he does not have car problems, we are given P ( A ) = 1- . 8 = . 2, and P ( B | A ) = . 60. So P ( A &amp;amp; B c ) = P ( A ) P ( B c | A ) = (1- . 6) . 2 = . 08. 3. (a) First question: Using the binomial distribution, we want the probability of 2 successes with n = 5 and p = . 3. This is C (5 , 2) ( . 3) 2 ( . 7) 3 = . 3087. Second question: The probability of no more than 1 is f (0)+ f (1) = C (5 , 0) ( . 3) ( . 7) 5 + C (5 , 1)...
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## This note was uploaded on 06/18/2009 for the course STAT Pstat 5E taught by Professor Landrigan during the Fall '08 term at UCSB.

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