6. Alice's Shop in Oxford, UK, is one of the most famous little shops in the world. It sells Alice in Wonderland themed gifts, souvenirs and memorabilia. One of the popular items is the Tea Party paper bookmark. The average of the Tea Party paper bookmark sold in a week is 2100 units. Supposed the weekly demand is approximately normally distributed, with a standard deviation of 200 units. The manager wants to limit the probability of being out of stock of the Tea Party paper bookmark. Please help to solve his problems below. You need to show your calculations. Remember to use four decimal places.