Question

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 ?

Answer 1

"n choose k" gives you the number of possible unique combinations...

n!/(k!(n-k)!)

n=number of elements to choose from and k=the number of elements that you choose...in this case:

7!/[2!(7-2)!]

7!/[2!5!]

21

There are 21 possible different two question combinations that she can pick.