If It isnt too much trouble, I had one more question.

Consider a transformed variable Wi, where Wi=a+bXi. Calculate the sample mean and variance of Wi, in terms of the sample mean and variance of Xi.

So in terms of Xi, we would have Xi=Wi-a/b

So if we take the sample mean formula Xbar= ∑i-n Xi/n, and replace Xi with Wi, is that what the question is asking for or is it something completely different.?

If you wanted to remember this for long time. Try to solve this using some example.. this will give more insight of the calculation.

ex: X1=5, X2 =2 ,X2 =1 here n = 3

Good idea, I'm going to do that.