The average inventory (in units) in the system is

Question

The throughput rate of  production system is 20 units per hour. The verge flow time is 30 minutes and he cycle time is 3 minutes. The average inventory (in units) in the system is                                                    

      (a) 1.5                                                                 (b) 9

      (c) 10                                                                  (d) 11.33