4- Demand for devils food whipped-cream layer cake at a local pastry shop can be approximated using a normal distribution with a mean of 24 and standard deviation of 4. The manager estimates it costs $9 to prepare each cake. Fresh cakes sell for $21. All day-old cakes sell for $6. At this price, there is an ample demand for day-old cakes. What is optimal service level?

Select one:

a. 0.8

b. 1%

c. 0.8%

d. 1

e. 0.2%

f. 0.2