## Problem of the Day #239: Connecting Points on a CircleNovember 13, 2011

Posted by Billy in : potd , trackback

Albert has $20$ distinct points evenly spaced on the circumference of a circle. He draws $10$ line segments that connect each point to exactly one other point. What is the expected value of the number of intersections there will be? Note that this is not the same as asking how many intersection points there will be.