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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 ?

Respuesta :

irspow
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!)

21


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