Simplify Var and Expected value?

Suppose E(X) = 5 and Var(X) = 3.

FIND:

a) Var(2x+4)

___________MY ATTEMPT_____________

I used this formula from Wikipedia.

Var(ax+b) = Var(ax) = a^2Var(x)

Therefore,

2^2 Var(x) = 4*3 = 12

__________________________________

Someone told me the answer is 10, I dont know why.

Any tips

Thanks

Re: Simplify Var and Expected value?

Quote:

Originally Posted by

**blackZ** Suppose E(X) = 5 and Var(X) = 3.

FIND:

a) Var(2x+4)

___________MY ATTEMPT_____________

I used this formula from Wikipedia.

Var(ax+b) = Var(ax) = a^2Var(x)

Therefore,

2^2 Var(x) = 4*3 = 12

__________________________________

Someone told me the answer is 10, I dont know why.

Any tips

Thanks

12 is right.

CB