[商管] [統計] 98逢甲國貿
題目: Two coins are simultaneously tossed until one of them comes up a head
and the other a tail. The first coin comes up a head with probability
1/3 and the second with probability 1/2. All tosses are assumed
independent. Let X be the number of tosses until the game is over.
(A) Find the expected value and the variance of X.
(B) Given the X is greater than 3, what is conditional probablity that X is
greater than 5?
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個人想法: 這題我覺得是用幾何分配 X~Geo(p=1/6)
pmf為 1/6 * (5/6)^(x-1) x=1,2,...,∞
但是之後就卡住了 因為不會做x在指數的期望值和變益數...
b小題則是沒有頭緒 我想是這樣 P(X>5︳X>3) 但是看起來就有問題
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◆ From: 218.170.6.180
※ 編輯: wbesjdje 來自: 218.170.6.180 (03/04 08:47)
※ 編輯: wbesjdje 來自: 218.170.6.180 (03/04 08:55)
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03/04 08:59, , 1F
03/04 08:59, 1F
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03/04 10:17, , 2F
03/04 10:17, 2F
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03/04 10:18, , 3F
03/04 10:18, 3F
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03/04 10:19, , 4F
03/04 10:19, 4F
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03/04 10:20, , 5F
03/04 10:20, 5F
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03/06 16:50, , 6F
03/06 16:50, 6F