3 years ago

How many different combinations of two can be made from 80 people?

1 answer:

3 0

Plugging directly into the combination formula, the answer is $\binom{80}{2}=\frac{80!}{2!78!}=\frac{80\cdot 79}{2\cdot 1}=40\cdot 79=\boxed{3160},$ where we have cancelled out common factors.

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