2. A music store sells a best-selling compact disc. The daily demand (in number of units) for the disc is approximately normally distributed with mean 200 discs and standard deviation 20 discs. The cost of keeping the discs in the store is $.04 per disc per day. It costs the store $100 to place a new order. There is a 7-day lead time for delivery. Assuming that the store wants to limit the probability of running out of discs during the lead time to no more than .02, determine the store's optimal inventory policy.