Maharashtra State BoardHSC Arts 12th Board Exam
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Given is X ~B(N,P) - Mathematics and Statistics

Sum

Given is X ~ B (n,p)

If E(X) = 6,Var(X) = 4.2 , find n and p.

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Solution

E(X) = 6 , Var(X) = 4.2 ,E(X) np,       Var(X) = npq

`therefore ("Var"("X"))/("E"("X")) = "npq"/"np" = "q" = 4.2/6 = 0.7          therefore "q" = 0.7`

`therefore "p"=1-"q"=0.3`

Now , np = 6

`therefore "n" = 6/"p" = 6/0.3 = 20`

Concept: Variance of Binomial Distribution (P.M.F.)
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