Question

If E(X) = 10 and SD (X) = 12, then find E(X2 ).

Answer 1

We know that ; *.D.(X) = √var(x)

Squaring both the sides,

[*.D (X)]2 = E(X2 ) – [E(X)]2

By substituting ; 122 = E (X2 ) – (10)2

∴ E(X2 )= 144 – 100 = 44.