Two operators are being considered for a particular job. The first operator will be paid at a rate of $10/hour and will have an exponentially distributed service time with a mean of 10 minutes. The second operator will be paid at a rate of $16/hour and will have a normally distributed service time with a mean of 8 minutes and a standard deviation of 2 minutes. Customers arrive at a Poisson rate of 5 per hour and have a cost of $10/hour spent in the system. Which operator minimizes expected cost?