Evaluate $\dfrac{n!}{r! (n-r)!}$ when $n = 5$ and $r = 2$.
A$15$
B$5$
C$10$
D$20$
Answer & Solution
Correct answer: C. $10$
$\dfrac{5!}{2! \cdot 3!} = \dfrac{120}{2 \cdot 6} = \dfrac{120}{12} = 10$. This equals $\binom{5}{2} = 10$.
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