Sweet Treats Sells Its Extra- Large Cupcakes for $10 Each

Sweet Treats sells its extra- large cupcakes for $10 each and the firm has a constant marginal cost of $6 per cupcake, which is equal to its (constant) average total cost. If Sweet Treats does not sell a cupcake the day it is produced, it is sold as day- old for $4. Sweet Treats should hold the number of cupcakes in inventory that makes the probability of selling that quantity of cupcakes or more equal to_______ .

A) 0.66
B) 0.33
C) 0.50
D) 0.75