A) Suppose you independently flip a coin 6 times and outcome of each toss can be either head or tails. Calculate the probability that you obtain exactly 3 heads?
B) If failures of the electronic device occur according to a Poisson distribution with an average of 3 failures every 12 months,calculate the probability that there will be more than one failure during a particular month.
Maths ,請用英文答加步驟?
2016-06-07 10:49 am
回答 (1)
2016-06-07 11:07 am
✔ 最佳答案
(A)P( exactly 3 heads )
= C(6,3) / 2^6
= 20 / 64
= 5 / 16 ..... Ans
(B)
Let X denotes the number of failures
λ
= 3 failures every 12 months
= 3/12 failures per month
= 0.25 failures per month
P( X = x )
= λ^x * e^(-λ) / x !
= 0.25^x * e^(-0.25) / x !
P( X > 1 )
= P( X ≧ 2 )
= 1 - [ P(0) + P(1) ]
= 1 - e^(-0.25)*( 1 + 0.25 )
= 1 - 1.25*e^(-0.25)
≒ 0.0265 ..... Ans
收錄日期: 2021-05-02 14:09:27
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