Jen's commute to work requires that she take the blue subway line, then transfer to the red line. the length of the trip on the blue line has a mean of 18 minutes with a standard deviation of 2 minutes. the red line trip takes 12 minutes with a standard deviation of 1 minute. the waiting time between when she gets off the blue line and her red line train arrives has mean of 10 minutes and a standard deviation of 5 minutes. assume (perhaps unrealistically) that these times are independent random variables. what are the mean and standard deviation of her entire commute?