SOLUTION: A test has 20 questions and students are asked to answer only 7 of them. In how many ways can a student choose the seven?

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Question 251382: A test has 20 questions and students are asked to answer only 7 of them. In how many ways can a student choose the seven?
Found 2 solutions by vleith, edjones:
Answer by vleith(2983) About Me  (Show Source):
You can put this solution on YOUR website!
For the first choice, the student can pick any one of 20 choices. Now there are 19 questions left to choose from.
For the second choice, the student can pick any one of the remaining 19 questions. Now there are 18 questions left
Keep doing that same process until you have picked 7 questions.
20%2A19%2A18%2A17%2A16%2A15%2A14 now just multiply and get your answer

Answer by edjones(8007) About Me  (Show Source):
You can put this solution on YOUR website!
nCr=n!/((n-r)!r!) Combination of n things taken r at a time.
20!/(13!*7!)
=77,520 ways
.
Ed