Gainesville Cigar stocks Cuban cigars that have variable lead times because of the difficulty in importing the product:

lead time is normally distributed with an average of $6$ weeks and

a standard deviation of $2$ weeks. Demand is also a variable and

normally distributed with a mean of $200$ cigars per week and a

standard deviation of $25$ cigars.

a$)$ For a $90\%$ service level, what is the ROP?

b$)$ What is the ROP for a $95\%$ service level?

c$)$ Explain what these two service levels mean. Which is

preferable?