1) after n days, what is expected value of number of first type coupons.
2) after n days, what is the expected value of number of types of coupons.
For the first one, I've considered decent and just did a random variable X that is an indicator for receving a first type coupon, and I just calculate E[$\Sigma$Xi] and get 1 and thats the expected value for the first question. (I think it is the answer).
Now the second questions is a bit tricky, could use some help to get me going. Thanks!