An automobile company assembles cars in a plant and purchases batteries from a supplier at the cost of $45/battery. The average flow time of cars from start to finish in the plant is 12 hours and the plant assembles 600 cars/day, operating 24 hours/day. Each car uses one battery and the cars are shipped to the dealers soon after they are made. The company holds 300 batteries in raw material inventory at the plant as a buffer. What is the total number of batteries in the plant on average?
a. less than 200
b. between 201 and 500
c. between 501 and 800
d. more than 800