There are seven shuffled question cards left in a game. Kim has to pick two of them and answer them both correctly to win. What is the greatest number of different pairs of question cards she can pick?

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Mathematics

Guest

26 September, 11:43

There are seven shuffled question cards left in a game. Kim has to pick two of them and answer them both correctly to win. What is the greatest number of different pairs of question cards she can pick?

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Enzo · Answer 1

The order does not matter so you use the "n choose k" formula ...

n! / (k! (n-k) !) where n=number of cards and k equal the number you are going to choose ... so:

7! (2! (7-2) !)

7! / (2!5!)

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