A burger stall owner must make a single order for burgers. Each burger costs the owner $13 and leftover burgers are marked down to $5 for quick sale. Loss of goodwill from customers if burgers run out is $28.5/burger. Estimated sales are given with the following probabilities:
Number: 40, 50, 60, 70, 80, 90, 100
Probability: 0.08, 0.12, 0.14, 0.23, 0.17, 0.14, 0.12