12-32 The Clear Brook High School band is holding a car wash as a fund-raiser to buy new equipment. The average time to wash a car is 4 minutes, and the time is exponentially distributed. Cars arrive at a rate of one every 5 minutes (or 12 per hour), and the num- ber of arrivals per time period is described by the Poisson distribution. (a) What is the average time for cars waiting in the line (b) What is the average number of cars in the line? (c) What is the average number of cars in the system? (d) What is the average time in the system? (e) What is the probability there are more than three cars in the system?