7. Two airplanes are flying in the same direction in adjacent parallel corridors. At time t = 0, the first airplane is 10 km ahead of the second one. Suppose the speed of the first plane (km/h) is normally distributed with mean 520 and standard deviation 10 and the second plane's speed, independent of the first, is also normally distributed with mean and standard deviation 500 and 10, respectively. a) What is the probability that after 2 h of flying, the second plane has not caught up to the first plane? b) Determine the probability that the planes are separated by at most 10 km after 2 h