How do I calculate the PDF of someone's earning followed by their mean and variance? This is the question: Given density function f(x) = 2.5 if 0.1 < x < 0.5 0 otherwise The person is paid by the # of jobs they finish rather than by the hour. They get 10$/job. Calculate the density function of his earnings per hour, then their mean and variance. What I did so far was integrating 2.5 from 0.2 to 0.4 and got an answer of 0.5. I am a bit confused on what to do with my answer and the 10$/job property. Any help would be great thanks.