2. (6 points) Suppose you sell three types of donuts: plain, nut covered and chocolate covered. The daily demand of each type of donuts is normally distributed and independent of each other. The means and standard deviations are given in the following table: Mean Standard deviation Plain 16 4 Nut covered 20 10 Chocolate covered 25 5 Assume that the production lead time of making donuts is zero, and you replenish your inventory of donuts every morning (i.e. review period is one day). Besides, you want to achieve a service level of 80% for each type of donuts.