Question

Given X ~ B(n, P) if n = 10 and p = 0.4, find E(x) and Var(X).

Answer 1

Given: n = 10 and  p = 0.4

∴ q = 1 - p = 1 - 0.4 = 0.6

∴ E(X) = np

= 10(0.4) = 4

∴ Var(X) = npq

= 10(0.4)(0.6) = 2.4

Hence, E(x) = 4, Var(X) = 2.4