=10.27. The Andes Mining Company mines and ships copper ore. The company’s sales manager, Juanita Valdes, has been using the moving-average method based on the last three years of sales to forecast the demand for the next year. However, she has become dissatisfied with the inaccurate forecasts being provided by this method.

The annual demands (in tons of copper ore) over the past 10 years are 382, 405, 398, 421, 426, 415, 443, 451, 446, 464.