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gaoyouya银虫 (小有名气)
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[求助]
有关概率分布的问题！十分着急！
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我现在在美国读研，是化学专业，正在学probability and statictis ,本身不是数学专业的人但老师把我们当成了数学专业的人在教，所以很痛苦。这有三道题想请教请教你们。 1) Probability density function. Let X be a random variable that has the probability density function f (x) = （1/6）（5/6）^(x-1), where x = 1, 2, 3, …. a) Show that f (x) is normalized. b) Prove that the cumulative density function for this distribution is F(x) = 1− (5/6)^x c) Compute P(4 ≤ X ≤ 7) . d) Evaluate< x> . 2) Quality assurance. Electric switches are shipped in packages of eight switches. The probability that an item is defective is 0.1. a) Which distribution (binomial, Poisson, Gaussian) best describes this situation? Briefly explain your answer. b) What is the probability that a package contains at least one defective switch? List your answer to four decimal places. c) What is the probability that a package contains fewer than two defective switches? List your answer to four decimal places. 3) Full-width at half maximum. Prove that the full-width at half maximum Γ for a Gaussian distribution is equal to Γ = (2 ln(4))σ , where σ is the standard deviation. 可能对于你们来说很简单 请不要笑话我，我第一题真的就是算积分算不对。二三题也是半懂不懂的。 请问 谢谢！ |
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11楼2013-04-14 14:45:53
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