Test 2 Solution

# Test 2 Solution - STAT 230 Quiz #2 October 13, 2004 Mark...

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STAT 230 Quiz #2 October 13, 2004 Mark For all of the problems below, show your work in the space indicated! Family(last) Name: Given Name I.D. No.: Section No. [6] 1. Let P A 0.2 , P B 0.7, P A B 0.8. (a) P A B 0.1 and P A | B 1/7 Note that P AB P A P B P A B 0.9 0.8 0.1 Therefore P A | B P AB P B 0.7 1 7 (b) A and B are independent? True False X Explain: In this case we note that P AB P A P B so they are not independent. (c) A and B mutually exclusive? True False Explain: Since P AB 0, it follows that AB is not the empty set and so they cannot be mutually exclusive. [6] 2. In a true-false test with three questions, two points are given for each correct answer and one is subtracted for each incorrect answer. Let Y be the mark on the test of a student who guesses randomly for each of the three questions. Specify the possible values of Y and calculate the values of the probability function f y of Y and the cumulative distribution function F y of Y at each of these values. Provide your answer in the following table: y - 303 6 f y 1 8 3 8 3 8 1 8 F y 1 8 4 8 7 8 8 8 1

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[12] 3. A diagnostic test for a disease is such that for persons with the disease, the probability that they test postive is 0.95 and for those who do not have the disease, the
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## This note was uploaded on 10/21/2010 for the course STAT 230 taught by Professor Various during the Fall '06 term at Waterloo.

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Test 2 Solution - STAT 230 Quiz #2 October 13, 2004 Mark...

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