- Thread starter
- #1

- Apr 14, 2013

- 4,036

The random variables $X_1, X_2, \ldots , X_{10}$ are independent and have the same distribution function and each of them gets exactly the values $\pm 2$ and with equal probability.

We define the random variable $S=X_1+X_2+\ldots +X_{10}$.

I want to calculate $\mathbb{E}(S^2)$.

Could you give me a hint how we could calculate that? I don't really have an idea.