A new café wants to know how its town rates it (1 to 10), but the survey was done wherever people were easy to reach, so the crowd you asked isn’t the crowd you want. Write estimate(ratings, asked_chances, wanted_chances): your best guess of the average rating in the crowd you want. For each answer you got: its rating, how common that kind of person (student, worker, retiree) is in the crowd you asked, and how common in the crowd you want.