1.) A firm orders on average 400 wheels each month. Demand is normally distributed with standard deviation of the monthly demand being 20 wheels. The ordering cost is $8 per order. The cost to buy one wheel is $4 per wheel. Annual carrying costs are 50% of unit cost. The supplier lead time is 2 operating days. The firm operates 240 days per year, in other word, the firm operates 20 days each month. Each order is received from the supplier in a single delivery. There are no quantity discounts. Write your answer and then Round your answer up to the nearest number for future calculation. (e.g 9.6 => 10). Please clearly write down the formulation and calculation for your answers. Note: Here I make the time measures bolded for you to make you pay the attention to their differences. Please notice the difference in times measure units, so that you do not make mistake by doing calculations with different time measures. You need to convert the data to the same time measures before doing any calculation. Another useful tool is to summarize your data in a table, like what I did in the lecture
1i. The manager thinks that the safety stock of 30 wheels is too low and ask for your advices. What is the safety stock if the firm maintain a service level of 95%?
