The fast-food restaurant Five-Guys operates on national basis. The store manager of Five Guys on Iowa Street has to decide how many "Cheese Dogs" to make every day. He learns that daily demand for Cheese Dogs follows a normal distribution of mean 100 and standard deviation 16.

(c) What is the probability that the Cheese Dog sales is within 20% of its average value? [3 points]

(d) The shop manager must plan to get raw materials (e.g., breads) for making Cheese Dogs everyday morning. How many Cheese Dogs must he plan for a given day so that 90% of demand (on average) can be met from in-stock items? Hint: In-stock probability equals 0.9. [4 points]