That's actually a neat interview question. a) So you have people living uniformly distributed on a line of length 1. When you pick 2 at random, what's the aver

That's actually a neat interview question. a) So you have people living uniformly distributed on a line of length 1. When you pick 2 at random, what's the average distance from one to the other? b) How about if they live on a circle of circumference 1 (and you can only travel along the circumference)? c) How about if they live on a disk of circumference 1 (and you can travel straight across the disk)?