# Probability

You are given the set of letters ( A, B, C, D, E ). What is the probability that in a random five-letter string (in which each letter appears exactly once, and with all such strings equally likely) the letters A and B are next to each other?

1. 👍 0
2. 👎 0
3. 👁 1,305
1. Consider the AB combination as a single letter. Then there are 4!=24 ways to arrange the letters AB,C,D,E.

Since A-B can be arranged in two ways, there are 2*4! = 48 ways.

1. 👍 1
2. 👎 4
2. but what is the denominator?

1. 👍 4
2. 👎 0

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