1.For binomial rv X,mean =26.491 S.D.=3.8205.FindP(X=x)for the mode
2.If X~B(15,0.222) Find P(4≦X≦9)
Probability?
2016-12-18 7:02 pm
回答 (1)
2016-12-19 5:07 pm
✔ 最佳答案
1.E(X) = n p = 26.491
V(X) = n p ( 1 - p ) = 3.8205²
1 - p = 3.8205² / 26.491 ≒ 0.551
p = 1 - 0.551 = 0.449
n = 26.491 / p = 26.491 / 0.449 = 59
P( X = x ) = C(59,x) * 0.449^x * 0.551^(59-x) ..... Ans
2.
P( X = x )
= C(15,x) * 0.222^x * ( 1 - 0.222 )^(15-x)
= C(15,x) * 0.222^x * 0.778^(15-x)
P( 4 ≦ X ≦ 9 )
= Σ C(15,x) * 0.222^x * 0.778^(15-x) , from x = 4 to x = 9
≒ 0.20957 + 0.13156 + 0.06257 + 0.02295 + 0.00655 + 0.00145
≒ 0.435 ..... Ans
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https://hk.answers.yahoo.com/question/index?qid=20161218110229AAHNCrE