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Unformatted text preview: 3. There are 3 coins in a box. One is a twoheaded; another is a fair coin; and the third is a biased coin that comes up heads 75 percent of the time. When one of the 3 coins is selected at random and flipped, it shows heads. What is the probability that it was the twoheaded coin? (20) 4. Suppose only 40% of all drivers in a certain state regularly wear a seatbelt. A random sample of 500 drivers is selected. What is the approximate probability that between 180 and 230(inclusive) of the drivers in the sample regularly wear a seatbelt? (20) 5. A coin that when flipped comes up heads with probability p. Let X be the number of flips required until either heads or tails has occurred twice. Find the probability mass function of X. Find the expectation of X. (20)...
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This note was uploaded on 11/15/2008 for the course STATS 116 taught by Professor Staff during the Summer '07 term at Stanford.
 Summer '07
 Staff
 Statistics, Probability

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