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Unformatted text preview: Math331, Spring 2008 Instructor: David Anderson Section 1.3 and 1.4 Hw answers Homework: pgs. 23  25, #s 5, 10, 13, 17, 25. 5. Let A be the event that an investor invests in traditional annuities. Let B be the event that an investor invests in the stock market. Then we know P ( A ) = . 75 , P ( B ) = . 45 , P ( A B ) = . 85. We wish to know what percentage invest in both. Therefore we want P ( A B ) = P ( A ) + P ( B ) P ( A B ) = . 75 + . 45 . 85 = . 35. Technically, the answer is 35%. 10. We know that P ( A B ) = P ( A ) + P ( B ) P ( A B ). Therefore, after rearranging, we have P ( A B ) = P ( A ) + P ( B ) P ( A B ). But P ( A B ) 1 and so P ( A B )  1 . Thus, P ( A B ) = P ( A ) + P ( B ) P ( A B ) P ( A ) + P ( B ) 1 . 13. Let A be the event that a crime occurs during the day and B be the event that a crime occurs within the city. We are given that P ( A ) = . 25 and P ( B ) = . 8 and P ( A B c ) = . 1....
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This note was uploaded on 03/31/2008 for the course MATH 331 taught by Professor Anderson during the Spring '08 term at Wisconsin.
 Spring '08
 Anderson
 Math, Probability

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