Note: In this exam, we assume there are $52$ weeks in a year and $4$ weeks in a month.

Q$1-$Q$2$

Jack is planning on selling moon cake in Moon Festival. The cost of a moon cake is $$2\mathrm{.}5$ and Jack can sell it for $$5.$ After the Moon Festival, Jack has to reduce the price to $$1\mathrm{.}5.$ Jack forecast the demand to be normally distributed with mean of $200$ and standard deviation of $40.$

What is the unit cost of ordering too many moon cakes?

a$.$ $$1$

b$.$ $$3\mathrm{.}5$

c$.$ $$2$

d$.$ $$2\mathrm{.}5$