WAEC 2023 · Paper 1 · Q20

In how many ways can four Mathematicians be selected from six?

Worked solution (try it first)

A selection does not care about order, so use combinations.
$^{6}C_4 = \dfrac{6!}{4!\,2!}$ , which works out as $\dfrac{6 \times 5}{2} = 15$ .
So there are 15 ways, option A.