1. The linear trend equation yˆ = 120 + 4.8x has been developed, where yˆ = estimated sales (thousands of dollars) and x = 1 for the year 1999. What level of sales would be forecast for 2013; for 2015?
2. An appliance repair shop owner has fitted the quadratic trend equation yˆ = 90 + 0.9x + 3x2 to a time series of annual repair orders, with y = the number of repair orders and x = 1 for 2005. Forecast the number of repair orders for 2013; for 2015.
3. Based on annual truck rentals over the years, a rental firm has developed the quadratic trend equation yˆ = 450 + 20x + 7.2x2, with x = 1 for 2005. Forecast y for 2013; for 2015.
4. When exponential smoothing is used in fitting a curve to a time series, the approach is slightly different from its application to forecasting. Compare the appro- priate formulas and point out how they differ.