$12\mathrm{.}679.$ The J&B Card Shop sells calendars featuring a different colonial picture for each month. The once$-$a$-$year order for each year's calendar arrives in September. From past experience the September$-$to$-$July demand for the calendars can be approximated by a normal distribution with $=300$ and standard deviation $=20.$ The calendars cost $$6\mathrm{.}50$ each, and J&B sells them for $$15$ each. Use the Single Period Inventory Excel template in MindTap to answer the following:

a$.$ Suppose that J&B throws out all unsold calen$-$

dars at the end of July. How many calendars should be ordered?

b$.$ If $J$&$B$ sells any surplus calendars for $$1$ at the end of July and can sell all of them at this price, how many calendars should be ordered?