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1)

If  XB(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 D

Explanation:

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