SOLUTION: You need to get at least a B on a 20 question test. How many different combinations are there to consider?

Question 419525: You need to get at least a B on a 20 question test. How many different combinations are there to consider?
Answer by richard1234(7193) (Show Source): You can put this solution on YOUR website!
I think you are implying the number of ways to get a B (16 questions or better).

The number of ways to choose 16 questions out of 20 to answer correctly is simply 20C16. Hence, for 17, ..., 20 questions there are 20C17, 20C18, 20C19, and 20C20 ways. Add these up to obtain the total number of ways to get a B or better.
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