Suppose that Nicholas is a college senior with an 8 a.m. class he needs to attend regularly. But he is not a morning person and so leaves his apartment as late as possible to get to class on time. The time it takes to reach class depends on two traffic lights that he encounters on his drive. From past experience, he believes that the first light has a 0.7 probability of being green when he gets there and the second light has a 0.6 probability of being green when he gets there. He also believes that the colors of the two lights are independent