3. Paras International Inc. markets industrial lubricants through a sales force of 30 salespersons. They spend most of their time in the field, calling on customers. When a sale is made, it is necessary for the salesperson to call into the home office to check pricing, availability and delivery. These calls require an average of 10 minutes, exponentially distributed. Salesmen call in at the average rate of once every two hours. It costs the company Rs. 15 per hour to employ people in the home office who have the skills to handle the salespersons enquiries. The salespeople are highly trained, and their time is worth Rs. 50 per hour.

a. What is the arrival rate per salesperson per hour?

b. What is the service rate per hour?

c. How many people should be employed in the home office?