Question

Suppose x has a distribution with mean 10 and variance 4, y has a distribution with mean 20 and variance 9. you can find the mean of x + y with this information.

Answer 1

If this is a true/false question, then the answer is true. If you're supposed to find the mean of $X+Y$, then we get

$\mathbb E[X+Y]=\mathbb E[X]+\mathbb E[Y]=10+20=30$

since expectation is linear.