If E(X) = 4, E(X2) = 25, find V(5X – 9).

1.	If E(X) = 4, E(X2) = 25, find V(5X – 9).
Answer» V(5x-9)this is of the type V(aX+b)=a²V(X) V(5x-9) = 5². V(x) Here V(X) = E(X²) – [E(x)]² ; = 25 – 42 = 25 – 16 = 9 ∴ V(5×-9) = 5² . V(x) = 25(9) = 225

Answer»

V(5x-9)this is of the type V(aX+b)=a²V(X)

V(5x-9) = 5². V(x)

Here V(X) = E(X²) – [E(x)]² ;

= 25 – 42 = 25 – 16 = 9

∴ V(5×-9) = 5² . V(x) = 25(9) = 225

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