作者smallwhite28 (給我你的愛)
看板Statistics
標題[問題] 機率問題
時間Wed Mar 19 10:02:32 2008
元智下禮拜就要考試了
最近做了考古題，因為沒有答案，所以很多都不確定
可以請各位幫我解一下以下幾題 謝謝!!!
1. A person's wallet is missing and it is presumed that
is was equally likely to have been forgot in any of
three possible places .Let Wi denote the probability
the wallet will be found upon a search of the ith place
when the wallet is in the place, i=1.2.3 . Let F be the
event that a search of place 1 is unsuccessful; and let
Ri , i=1.2.3 ,be the event that the wallet is in the
place i .
(a)What is the probability of R2
(b)What is the probability of F,given that R2 has occurred
(c)What is the probability of F
(d)What is the probability of R1,given that F has occurred
2. Let X have a continuous distribution with density e^(-x)
for x > 0 and 0 for x < = 0. Let Y=[X] be the integer part
of X ,and let Z be in integer nearest to X. Find
(a)The probability mass function of Y
(b)The probability mass function of Z
(c)P(Y=Z)
(d)P(Y=2|Z=3)
(e)P(Z=2|Y=3)
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