A vending machine dispenses hot chocolate or coffee. Service time is 20 seconds per cup and is constant. Customers arrive at a mean rate of 63 per hour, and this rate is Poisson-distributed. a. Determine the average number of customers waiting in line. (Round your answer to 2 decimal places.) b. Determine the average time customers spend in the system. (Do not round intermediate calculations. Round your answer to 2 decimal places.)