50, 57, 62, 65, 70 evaluate each of the following. EXi EXi^2 (EXi)^2?

First, I assume you really meant to use the sigma symbol (∑) to represent a sum.

These are all really simple once you realize what they mean.

∑Xᵢ --> Add up all the terms
50 + 57 + 62 + 65 + 70 = 304

∑Xᵢ² --> Add up all the squared terms
50² + 57² + 62² + 65² + 70² = 18,718

(∑Xᵢ)² --> Add up all the terms and square the result. You've already figured out the sum (304), so just square it.
304² = 92,416

Notice the difference between the second and third results -- they are not the same.

Don’t know