I'm receiving a lecture on Modeling the Heart for about three weeks. We were assigned a problem which required us to find the mean Psa value.. Where Psa(t) = Psa(0)*exp(-t/(Csa*Rs)) and Psa(0) is the initial value, and Csa and Rs are constants. Now What i did is intergrate this like 1/T * Int(Psa(t),t=0..T). And I got the right answer. The second part of the problem wants us to approach it another way. They want us to evaluate the average of N equal spaced samples of Psa(T). and then take the lim N -> infinity. As a hint they remind us that Psa(T) forms a finite geometric series. I can't remember any of this from Calculus II. Can someone show me how to do it? Thanks.