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Problem 6-42 Continuation of Preceding Problem; Computing Least-Squares Regression Estimates; Comparing Multiple Methods (Appendix) (LO 6-1, 6-2, 6-5, 6-6, 6-9) [The following information applies to the questions displayed below.) Martha's Vineyard Marine Supply is a wholesaler for a large variety of boating and fishing equipment. The company's controller, Mathew Knight, has recently completed a cost study of the firm's material handling department in which he used work measurement to quantify the department's activity. The control factor unit used in the work-measurement study was hundreds of pounds of equipment unloaded or loaded at the company's loading dock. Knight compiled the following data. Month January February March April May June July August September October November December Units of Activity (hundreds of pounds of equipment loaded or unloaded) 3,400 3,200 2,900 2,600 3,800 4,000 3,600 3,400 4,200 2,700 2,800 3,000 Material Handling Department Costs $13,300 12,900 12,050 11,800 12,700 14,950 13,600 13,000 14,040 11,850 12,950 12,950 Problem 6-42 Part 2 2. Complete the least-squares regression equation for the department's costs. (Do not round intermediate calculations. Round variable cost per unit to 2 decimal places and other answer to the nearest whole dollar amount.) Total monthly cost = per unit of activity