1. The problem statement, all variables and given/known data As the title indicates. I'm given two independent exponential distributions with means of 10 and 20. I need to calculate the probability that the sum of a point from each of the distributions is greater than 30. 2. Relevant equations X is Exp(10) Y is Exp(20) f(x) = e^(-x/10) / 10 g(y) = e^(-x/20) / 20 3. The attempt at a solution I think I need to find the distribution of X + Y and then integrate to find the cdf. I'm not sure how to go about that though.