Company has decided to develop cost formulas for its major over- head activities. Wheeler uses a highly automated manufacturing process, and power costs are a significant manufacturing cost. Cost analysts have decided that power costs are mixed; thus, they must be broken into their fixed and variable elements so that the cost behavior of the power usage activity can be properly described. Machine hours have been selected as the activity driver for power costs. The following data for the past eight quarters have been collected:

Required:
1. Prepare a scattergraph by plotting power costs against machine hours. Does the scatter-graph show a linear relationship between machine hours and power cost?
2. Using the high and low points, compute a power cost formula.
3. Use the method of least squares to compute a power cost formula. Evaluate the coefficient of determination.
4. Rerun the regression and drop the point (20,000; $26,000) as an outlier. Compare the results from this regression to those for the regression in Requirement 3. Which is better?

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Quarter Machine Hours Power Cost 20,000 25,000 30,000 22,000 21,000 18,000 24,000 28,000 $26,000 38,000 42,500 35,000 34,000 31,400 36,000 42,000 4