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Unformatted text preview: they have one of each sex. Ignoring the possibility of twins and supposing that each trial is independent and results in a boy or a girl with probability 1 / 2, what is the expected value of the number of children they will have? 2.4. Suppose we pick a month at random from a nonleap year calendar and let X be the number of days in the month. Find the mean and variance of X . 2.5. Can we have a random variable with EX = 3 and EX 2 = 8? 2.6. In a class of 19 students, 7 will get As. In how many ways can this set of students be chosen?...
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 Fall '08
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 Math, Probability

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