2 distinct vertices of an octagon are chosen at random. What is the probability that they are adjacent?

The total number of pairs = C(8,2) = 28

Adjacent pairs

(1,8) (1,2) (2, 3) (3,4) (4, 5) (5, 6) (6, 7) (7, 8)

So....the probability is

8 / 28 =

2 / 7

An octagon has 8 vertices, and the question says, "2 distinct vertices of an octagon are chosen at random. What is the probability that they are adjacent? So, this is just 8C2=28 total pairs. Thus, the answer is 8/28=4/14=2/7