A manager intends to order a new machine and must now decide on the number of spare parts to order along with the machine. The parts cost $483 each and have no salvage value. The manager has compiled the frequency distribution for the probable usage of spare parts:5 spare parts with frequency 0.13;6 spare parts with frequency 0.17;7 spare parts with frequency 0.16;8 spare parts with frequency 0.16; and 9 spare parts with frequency 0.38. For what range of shortage costs would stocking 7 spare parts constitute an optimal decision ?

a. Between 207and 411.4

b. Between 103.5and 205.7

c. Between 310.5and 617.2

d. Between 248.4and 493.7