The management at a fast-food outlet is interested in the joint behavior of the random variables Y, defined as the total time between a customer's arrival at the store and departure from the service window, and Y2, the time a customer waits in line before reaching the service window. Because Y, includes the time a customer waits in line, we must have Y2 Ys. The relative frequency distribution of observed values of Y, and Y; can be modeled by the probability density function -{" e, 0 y y < 00, elsewhere f(91.92)= with time measured in minutes. Find a P(Y, <2, Y > 1). b P( 22). c P(Y-Y21). (Notice that Y-Y denotes the time spent at the service window.)