Answer:
Since a, e, m, and x are distinct letters, there are 4 ways to choose the first letter, there are 3 ways to choose the second letter, there are 2 ways to choose the third letter, and there is 1 way to choose the fourth letter. So there are
4 × 3 × 2 × 1 = 24 ways to randomly type these four letters. Since one of these ways is the word "exam", the probability of typing the word "exam" is 1/24.