Rachel and Robert run on a circular track. Rachel runs counterclockwise and completes a lap every seconds, and Robert also runs counterclockwise and completes a lap every seconds. Both start from the start line at the same time. At some random time between minutes and minutes after they begin to run, a photographer standing inside the track takes a picture that shows one-fourth of the track, centered on the starting line. What is the probability that both Rachel and Robert are in the picture?
