For the data in Problem 7.3, pretend that the index increases linearly in time and use linear regression to obtain an equation to forecast the index value as a function of time. Using “volume”

as a weight variable, obtain a weighted least squares forecasting equation. Does weighted least squares help the fit? Obtain a recent value of the index (from a newspaper). Does either forecasting equation predict the true value correctly (or at least somewhere near it)? Explain.