SOLUTION: On a test, a student is to select 11 out of 13 questions. In how many ways can this be done?

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Question 968531: On a test, a student is to select 11 out of 13 questions. In how many ways can this be done?
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
On a test, a student is to select 11 out of 13 questions. In how many ways can this be done?
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He picks 2 to leave out.
--> 13*12 = 156
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But, picking A & B to leave out is the same as B & A.
--> 156/2 = 78 ways.