Question

How many different station call letters can be made if repetition is not allowed?

Answer 1

Since repetition is not allowed, we need to use a permutation:

$\begin{gathered} P=(n,r)=\frac{n!}{(n-r)!} \\ P=(27,3)=\frac{27!}{(24)!}=17550 \\ \end{gathered}$

Since the first letter is K or W:

$17550\times2=35100$