Access the data, labeled Retafl_Sales, from the text website. Estimate the model y = 0 + 1x

Access the data, labeled Retafl_Sales, from the text website. Estimate the model y = β0 + β1x + β2d1 + β3d2 + β4d3 + ε, where y is Retail Sales, x is GNP, d1 is a dummy variable that equals 1 for quarter 1, d2 is a dummy variable that equals 1 for quarter 2, and d3 is a dummy variable that equals 1 for quarter 3. Compare the 95% confidence intervals for expected sales (in $ millions) in quarter 2 and quarter 4 with GNP equal to $13,000 billion.