A lab provides ultrasound service to patients. The service process consists of two steps:

1. Registration. Performed by a receptionist (Salary rate = $25/hr; Process time = 6 minutes/patient)
2. Ultrasound scan. Performed by a technician (Salary rate = $35/hr; Process time = 20 minutes/patient)

Note that the ultrasound images need to be read by radiologists, but we assume that they have an ample capacity and thus will not model the role in the service process.

Currently, the lab has 2 receptionists and 2 technicians. The manager anticipates demand to grow to 14 patients/hr in the near future. Thus, he plans to hire more receptionists and/or technicians to increase the service capacity to at least 14 patients/hr. What would be theextra payroll cost (in dollars per hr)?