Rachel and Robert run on a circular track. Rachel runs counterclockwise and completes a lap every 70 seconds, and Robert runs clockwise and completes a lap every 90 seconds. Both start from the same line at the same time. At some random time between 15 minutes and 16 minutes after they begin to run, a photographer standing inside the track takes a picture that shows one-sixth of the track, centered on the starting line. What is the probability that both Rachel and Robert are in the picture?
