# Expected value of discrete and continuous random variables.

I wanted to confirm something. If we are given a discrete random variable's CDF and we want to find it's expected value we use summation formula. And for continuous we integrate the CDf to find expected value. Right?

• You mean the pdf? Nov 28 '18 at 7:48
• this is what is confusing me. in continuous do we use pdf or cdf? Nov 28 '18 at 8:02
• In general $\int xdF(x)$ in both cases. If the rv is discrete then this integral can be written as a summation. Nov 28 '18 at 8:06
• The pdf in both cases Nov 28 '18 at 8:40
• I'd like to direct you to this site: newonlinecourses.science.psu.edu/stat414/node/126 Jan 21 '19 at 11:44