Marie and her friends leave for a basketball game at 6: The game starts uniformly between 7:00 and 7:10 pm. There are 10 stoplights between Marie's...

Marie and her friends leave for a basketball game at 6:50 p.m. The game starts uniformly between 7:00 and 7:10 pm. There are 10 stoplights between Marie’s house and the arena. Independently with probability 1/2 a light is green or with probability 1/2 the light is red and she must wait for some uniform time between 0 and 30 seconds. If all the lights are green it takes Marie 10 minutes to drive to the arena. What is the probability that her and her friends arrive on time?