Math Help - expected value question

1. expected value question

Hello-

I have a quick question if anyone out there can help:

I am told that E(x) = 8 and var (x) = 4

the question is: determine E(y) for y=3x^2 + 2

My answer is E(y) = 3*e(x^2) + 2

which works out to be 3*64+2 = 194

i realize that e(x^2) does NOT equal e(x)^2

am i overthinking this?

2. Originally Posted by rogersd425
Hello-

I have a quick question if anyone out there can help:

I am told that E(x) = 8 and var (x) = 4

the question is: determine E(y) for y=3x^2 + 2

My answer is E(y) = 3*e(x^2) + 2

which works out to be 3*64+2 = 194

i realize that e(x^2) does NOT equal e(x)^2

am i overthinking this?
$Var(X) = E(X^2) - [E(X)]^2$

$\Rightarrow 4 = E(X^2) - 8^2 \, ....$