# Given X ~ B(n, P) if n = 10, E(X) = 8, find Var(X). - Mathematics and Statistics

Sum

Given X ~ B(n, P) if n = 10, E(X) = 8, find Var(X).

#### Solution

Given: n = 10, E(X) = 8

E(X) = np

∴ 8 = 10p

∴ p = 8/10 = 4/5

∴ q = 1 - p = 1 - 4/5 = 1/5

Var(X) = npq

= 10 xx 4/5 xx 1/5 = 8/5

Hence, Var(X) = 8/5

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