DeMarco Company is developing a cost formula for its packing activity. Discussion with the workers in the packing department has revealed that packing costs are associated with the number of customer orders, the size of the orders, and the relative fragility of the items

(more fragile items must be specially wrapped in bubble wrap and Styrofoam). Data for the past twenty months have been gathered:

Required:
1. Using the method of least squares, run a regression using the number of orders as the independent variable.
2. Run multiple regression using three independent variables: the number of orders, the weight of orders, and the number of fragile orders. Which regression equation is bet¬
ter? Why?
3. Predict the total packing cost for 25,000 orders, weighing 40,000 pounds, with 4,000 frag¬
ile orders. Prepare a 99 percent confidence interval for this estimate of total packing cost.
4. How much would the cost estimated for Requirement 3 change if the 25,000 orders weighed 40,000 pounds, but only 2,000 were fragile orders?

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Month Packing Cost Number of Orders Weight of Orders Number of Fragile Orders 123456 $ 45,000 11,200 24,640 1,120 58,000 14,000 31,220 1,400 39,000 10,500 18,000 1,000 35,600 9,000 19,350 850 90,000 21,000 46,200 4,000 6 126,000 31,000 64,000 5,500 7 90,600 20,000 60,000 1,800 8 63,000 15,000- 40,000 750 9 79,000 16,000 59,000 1,500 10 155,000 40,000 88,000 2,500 11 450,000 113,500 249,700 11,800 12 640,000 150,000 390,000 14,000 13 41,000 10,000 23,000 900 14 54,000 14,000 29,400 890 15 58,000 15,000 30,000 1,500 16 58,090 14,500 31,900 1,340 17 80,110 18,000 50,000 3,000 18 123,000 30,000 75,000 2,000 19 108,000 27,000 63,450 1,900 20 76,000 18,000 41,400 1,430