I'm having trouble identifying what type of problem the following question is:
A student is trying a new study strategy for the final exam. There are four topics to study for the exam and each day he picks a topic at random to study (and so he may study the same topic multiple times). Let T be the random variable corresponding to the number of days he'll study before he has studied every topic
Find E(T) and Var(T).
The answer to this question is provided to me but I don't know how the answer is obtained. I incorrectly tried to use a distribution, which obviously failed. Is this a variation of the balls in the bin problem? How can I locate this problem so that I know which approach to take (I have my exam in 2 hours).
Thanks! Just having trouble wrapping my head around this particular problem.