Cars arrive at the Zippy-Lube oil change center following a Poisson distribution at an average rate of 4.5 cars per hour. The average service time per car is 10 minutes with a standard deviation of 3 minutes. A new automated oil dispensing device costs $5,000. The manufacturer's representative claims this device will reduce the average service time by 3 minutes per car. (Currently, employees manually open and pour individual cans of oil.) The hourly cost of server is $7 and the hourly cost of waiting is $12. The owner wants to analyze the impact the new automated device would have on his business and determine the pay back period for this device.