Say we have a random variable A and another random variable B. A is described as a row of 50% chances between either getting a beer or a coffee, that have no influence on each other. Let's say the expectation of A is time when we first get a beer. B is A+1. I know that E[B] is therefore 3. Additionally, I have a third random variable named C. To make it fun, this one can take any real value between 0 and 5 with equal probability. That means E[C] = 2.5 Now what I'm doing is to make up a fourth random variable called D. D will be the sum of a bunch of C. How many C's are added depends on B. For example, if B turns out to be like its expectation, then I add three C's with each other. And the result of that will be D. Now my question is: what value should I expect for the mean of D and the variance of D? And my second question is: do you like beer