Problem 13-13 A mail-order house uses 18,000 boxes a year. Carrying costs are 60 cents per box a year, and ordering costs are $96. The following price schedule applies. Number of Boxes Price per Box 1,000 to 1,999 $1.25 2,000 to 4,999 1.20 5,000 to 9,999 1.15 10,000 or more 1.10 a. Determine the optimal order quantity. (Round your intermediate calculations to 2 decimal places and final answer to the nearest whole number.) Optimal order quantity boxes b. Determine the number of orders per year. (Round your answer to 1 decimal place.) Number of order per year