D and L produces high quality plain colored t-shirts and polo jerseys which it sells at its retail outlets across the island. These products are in high demand throughout the year as many companies and individuals purchase them singly and in bulk to have prints put on them.

At one of the retail outlets, located in Chaguanas, the inventory manager notices that he often runs out of stock of black polo jerseys, more often than he likes. He decides that he would aim for a service probability of 97.5%. He places order every other Friday. Each order for the polos takes 5 days to arrive. Past records have shown that there is a daily demand of 20 with a standard deviation of 4. He would also like to ensure that every time he places an order, that he has in stock, 60 of the black polos on hand. The outlet is opened for 250 days for the year. It costs the outlet $80 dollars to place an order the polos.

What size order should the manager place when ordering the black polos?