1) If X∼B(n,p) with n=10 , p=0.4 , then E(X)2= A) 4 B) 2.4 C) 3.6 D) 18.4 Answer: Option DExplanation:Given , n=10 and p=0.4 ∴ q=1-p=1-0.4=0.6 E(x) = np=10(0.4)=4 σ2 = npq= 10(0.4)(0.6)=2.4 We know that, σ2=E(X2)−(E(X))2 ∴ E(X2)=σ2+(E(X))2 ⇒ E(X2)=24+(4)2 =2.4+16=18.4