1. A rod is divided to n segments randomly, what is the probability that the segments can form a polygon. 2. Randomly choose three points on a circle, what is the probability that they form an acute triangle ? 3. Cannot remember the detailed description, the main issue is to figure out the relation between the cdf/pdf and f(u)=E(max{u-x,0}), with x being the random variable. 4. 2n random numbers are laid in a row. We take turns to take a number. Each time, one can choose from the number on the tail or the head. The one with the bigger summation wins the game. If I go first, can I always win (or tie)?