In a coupon collecting game there are two different kinds of coupons, the green and the yellow ones. Each kind has n different coupons. We want to gather only one kind: either all the green ones or all of the yellow ones. What is the expected number of "purchases" (steps) to get them for n=2 and n=3?

Okay Just to clarify, I am assumin gthat for example, when n = 2, there are 4 different kinds of cards, 2 yellow and 2 green.

And that when you 'purchase' you get one random card.

?

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Originally Posted by Capuchin

Okay Just to clarify, I am assumin gthat for example, when n = 2, there are 4 different kinds of cards, 2 yellow and 2 green.

And that when you 'purchase' you get one random card.

??

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Yes indeed, my mistake for not clarifying this. When n=2 there are 4 cards, 2 yellow and 2 green, and when n=3 there are 6 cards, 3 yellow and 3 green. And whne purchasing you get one card. :)