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(Coupon collector) Suppose there are 5 types of toys, which you are collecting o

ID: 3058988 • Letter: #

Question

(Coupon collector) Suppose there are 5 types of toys, which you are collecting one by one, with the goal of getting a complete set. When collecting toys, the toy types are random (as is sometimes the case, for example, with toys included in cereal boxes or included with kids meals from a fast food restaurant). Assume that each time you collect a toy, it is equally likely to be any of the 5 types. What is the expected number of toys needed until you have a complete set? Hints: (1) First find the expected number of toys until you have a first type, then the expected number of toys until you have a second type (after that you already have a first type), and so on (2) Related to Geometric model.

Explanation / Answer

(Coupon collector) Suppose there are 5 types of toys, which you are collecting one by one, with the goal of getting a complete set. When collecting toys, the toy types are random (as is sometimes the case, for example, with toys included in cereal boxes or included with kids meals from a fast food restaurant). Assume that each time you collect a toy, it is equally likely to be any of the 5 types. What is the expected number of toys needed until you have a complete set? Hints: (1) First find the expected number of toys until you have a first type, then the expected number of toys until you have a second type (after that you already have a first type), and so on (2) Related to Geometric model.