Thom Betow is the new manager of the materials storeroom for Manning Industries. Thom has been asked to estimate future monthly purchase costs for part# 18, used in two of Manning’s products. Thom has purchase cost and quantity data for the past 9 months as follows.

Estimated monthly purchases for this part based on expected demand of the two products for the rest of the year are as follows.
Month Purchase Quantity Expected
October........... 2,750 parts
November......... 3,260
December ...........2,610

Required
1. The computer in Thom’s office is down and Thom has been asked to immediately provide an equation to estimate the future purchase cost for part# 18. Thom grabs a calculator and uses the high– low method to estimate a cost equation. What equation does he get?
2. Using the equation from requirement 1, calculate the future expected purchase costs for each of the last 3 months of the year.
3. After a few hours Thom’s computer is fixed. Thom uses the first 9 months of data and regression analysis to estimate the relationship between the quantity purchased and purchase costs of part# 18. The regression line Thom obtains is:
y = $ 5,337.90 + 2.56X
Evaluate the regression line using the criteria of economic plausibility, goodness of fit, and significance of the independent variable. Compare the regression equation to the equation based on the high– low method. Which is a better fit? Why?
4. Use the regression results to calculate the expected purchase costs for October, November, and December. Compare the expected purchase costs to the expected purchase costs calculated using the high– low method in requirement 2. Comment on yourresults.

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Month January February March April May June July August September Cost of Purchase $13,950 11,600 15,200 13,100 11,800 12,750 12,350 10,100 13,400 Quantity Purchased 3,490 parts 2,480 3,600 3,250 2,390 2,780 2,970 1,900 3,050