Please be fast solve as early as possible

A book shop is planning to order calendars for sale starting in October. Only one order is placed. The calendars cost $1.50 and the shop sells them for $3 each. At the end of December, the shop reduces the calendar price to $1 and can sell all the surplus calendars at this price. The October-to-December demand can be approximated by a normal distribution with 2 = 500 calendars and E = 120 calendars. 1. What inventory model should be used to determine the order quantity to maximize the total expected prot? Why? 2. What is the optimal service level? 3. How many calendars should the shop order so as to maximize the total expected prot