For the control of vehicles at a traffic light, one needs to determine the length of the left-turn lane (right-turn lane in countries where vehicles are driven on the left). The occurrences of left...

For the control of vehicles at a traffic light, one needs to determine the length of the left-turn lane (right-turn lane in countries where vehicles are driven on the left). The occurrences of left (right) turns are assumed to have a Poisson distribution in time. The mean uninterrupted rate of left (right) turns is 160 per hour and the red light is on for 50 seconds. What is the expected number of vehicles awaiting a left (right) turn?