The quarterly sales data (number of copies sold) for a college textbook over the past three years follow ...

      The quarterly sales data (number of copies sold) for a college   textbook over the past three years follow. a. Compute   the linear trend equation for the deseasonalized data (to 2 decimal if   necessary).   Deseasonalized   Value =   +   Period         Compute the   forecast sales using the linear trend equation (to 1 decimal).   Forecast for   quarter 1    Forecast for   quarter 2    Forecast for   quarter 3    Forecast for   quarter 4    b. Adjust   the linear trend forecasts using the adjusted seasonal indexes computed in   part (c) (to the nearest whole number).   Forecast for   quarter 1    Forecast for   quarter 2    Forecast for   quarter 3    Forecast for   quarter 4