1. The problem statement, all variables and given/known data let X denote the vibratory stress (psi) on a wind turbine at a certain wind speed. the pdf is f(x;y) = (x/y^2)*(e^((-x^2)/(2y^2)) a) i need to prove that it is a pdf. b)assume y=100, what is the probabilty X is at most/least 200? whats prob X les than 200 2. Relevant equations 3. The attempt at a solution so i did part a part 1...f(x;y) is greter than 0 for all values... but for the integral of f(x)=1, i think i need to know how to integrate that, and i have no idea how!