Consider a retailer's inventory problem over multiple time periods. Assume the per-unit holding cost is $10 and the per-unit backlogging cost is $30. Demand in every time period is normally distributed with mean 100 and standard deviation 10. The beginning inventory of period 1 is equal to 100. Assume every order placed at the end of each period will arrive at the beginning of the next period. Build the Excel-based Monte Carlo simulation spreadsheet to test the optimal inventory ordering policy that minimizes the total holding and backlogging costs in expectation.