Chapter 8.2, Problem 16E

(a)

To determine

The number of ways in which two letters can be chosen from $\left\{\text{L, M, N, P}\right\}$ with repetition using a tree diagram.

(b)

To determine

The number of ways in which two letters can be chosen from $\left\{\text{L, M, N, P}\right\}$ without repetition using a tree diagram.

(c)

To determine

The number of combinations of four elements taken three at a time.