Solveeit Logo

Question

Question: In a P.D., E(x<sup>2</sup>)= 20, P(X=1) = ............

In a P.D., E(x2)= 20, P(X=1) = .........

A

2/e2

B

3/e2

C

4/e4

D

6/e4

Answer

4/e4

Explanation

Solution

V(x) + [E(x)]2 = 20

λ + λ2= 20

λ2 + λ - 20 = 0

(λ +5) (λ-4) = 0

λ = 4

P(X=1) = λe = 4e-4 = 4e4\frac { 4 } { \mathrm { e } ^ { 4 } } .