The decision sciences department is trying to determine whether to rent a slow or fast copier. The department belives that an employee's time is worth $15 per hour. The slow copier rents for $4 per hour and and it takes an employee an average of 10 minutes to complete coping ( Exponentially distributed). The fast copier rents for $15 per hour and it takes an employee an average of 6 minutes to complete coping. An average of 4 employees per hour need to use the coping machine ( interarrival times are exponential ). Which machine should the department rent?