One problem of eight solved in this week's homework.

I solved one problem now of eight problems to be solved. I also got my grade for last week's homework and have brought my grades up a little including not being tricked by an error in the textbook but instead relying on my own learning from the textbook. In this first problem I needed to show that a sum of identical and mutually independent exponential r.v.'s is a gamma distribution. I usually have had the first problem in this weekly homework done by Friday or Saturday of the previous week so I am behind but trying to race to completion by Thursday morning when this homework is due in class..