There's a circle that has a radius r = 1 and suppose you draw two points at random.

Assume:

they are uniformly distributed over its perimeter. (Recall that the perimeter of a circle has length 2xr.) Consider the smallest arc defined by the two points, and find the probability that its length is less than 7/3. (Hint: Without the loss of generality, fix one point and think of the other one as being uniformly distributed on the interval whose starting/terminating point is the first point.)