This is an example of a problem called the Coupon Collector problem (https://en.wikipedia.org/wiki/Coupon_collector%27s_problem https://en.wikipedia.org/wiki/Co

This is an example of a problem called the Coupon Collector problem (https://en.wikipedia.org/wiki/Coupon_collector%27s_problem https://en.wikipedia.org/wiki/Coupon_collector%27s_problem). Short version is that the expected value of number of pulls you'll need to collect all of the coupons (candy in this case) is nln(n), or about 16 pulls in this case. Of course some people are just going to be unlucky (as you demonstrated).