Question

Var (X)=2,if U=5x+2,then Var (U) is Equal to ??

I know its 50. but how to reach the final answer

Answer 1

Var(U)=50

Explanation:

Given

Var(X) = 2

We have to find

Var(U) when U = 5x+2

So,

When a variable is multiplied with an integer, the variance of that variable is multiplied with the square of that number i.e. Var(aX) = a^2 Var(X) This the property of variance.

As here x is multiplied with 5,

Var(5x) = 5^2 var(X) = 25*2 = 50

If the same integer is added to all the data values, there is no change in variance that is why the +2 will not affect the variance of U ..