There are $n$ persons sitting in a row. Two of them are selected at random. The probability that two

Question

There are $n$ persons sitting in a row. Two of them are selected at random. The probability that two selected persons are not together is

Professor PC Thomas Classes · Answer

Counting paired isolations establishes $\frac{2}{n}$ bounds. Subtracting uniformly deduces $1 - \frac{2}{n}$ probability.