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d: Try a 3-period weighted moving average and use Solver to determine the set of

ID: 3048955 • Letter: D

Question

d: Try a 3-period weighted moving average and use Solver to determine the set of weights that result in the best (lowest) MAPE

21A college student has iust completed her iunior year. The following table summarizes her grade-point av- erage (GPA) for each of the past nine quarters: SEMESTER GPA 2.4 2.9 3.1 3.2 3.0 2.9 2.8 3.6 3.2 YEAR Fall Winter Spring Fall Winter Spring Fall Winter Spring Freshman Sophomore Junior (a) Forecast the student's GPA for the fall semester of her senior year by using a three-period moving average. (b) Forecast the student's GPA for the fall semester of her senior year by using exponential smooth ing with -02. (c) Which of the two methods provides a more ac- curate forecast? Justify your answer.

Explanation / Answer

21)

Year Semester GPA MA Exp Smoothing Dev_MA Abs Dev_MA Dev_Exp Smoothing Abs Dev_Exp Smoothing Freshman Fall 2.4 2.4 Winter 2.9 2.8 2.4 0.1 0.1 0.5 0.5 Spring 3.1 3.066666667 2.5 0.033333333 0.033333333 0.6 0.6 Sophomore Fall 3.2 3.1 2.62 0.1 0.1 0.58 0.58 Winter 3 3.033333333 2.736 -0.033333333 0.033333333 0.264 0.264 Spring 2.9 2.9 2.7888 0 0 0.1112 0.1112 Junior Fall 2.8 3.1 2.81104 -0.3 0.3 -0.01104 0.01104 Winter 3.6 3.2 2.808832 0.4 0.4 0.791168 0.791168 Spring 3.2 2.9670656 0.2329344 0.2329344 3.01365248 MAD 0.138095238 MAD 0.3862928 As we can see that the MAD is less for 3 period moving average, it is a better forecasting method than exponential smoothing