Suppose that Winters’ method is used to forecast quarterly U.S. retail sales (in billions of dollars). At the end of the first quarter of 2010, the seasonal indexes are: quarter 1, 0.90; quarter 2, 0.95; quarter 3, 0.95; quarter 4, 1.20. Also, the current estimates of level and trend are 300 and 30. During the second quarter of 2010, retail sales are $360 billion. Assume α = 0.2, β = 0.4, and γ = 0.5
a. At the end of the second quarter of 2010, develop a forecast for retail sales during the third and fourth quarters of 2010.
b. At the end of the second quarter of 2010, develop a forecast for the first and second quarter of
2011.