1. The problem statement, all variables and given/known data I am doing a practice final exam in preparation of my actual final exam next week. Here is the link. I am doing problem number 2. http://www.math.stevens.edu/~ifloresc/Teaching/2011-2012/MA222S12/Final_Exam_Summer2011.pdf 3. The attempt at a solution So this seems pretty straight forward starting out, but I noticed that the PDF does not integrate to 1 as it should. So I redefined the function so that it does. Was this the correct thing to do? Because later in the problem I have more issues with finding the standard deviation. It appears as though I get a negative variance! Here is my work.. http://img43.imageshack.us/img43/9818/work1hm.jpg [Broken] If anyone could help me I would be so thankful!