"Let Yt be the sales during month t (in thousands of dol-lars) for a photography studio, and let Pt be the price charged for portraits during month t. The data are in the file P11_45.xlsx. Use regression to fit the following model to these data:Yt5a1b1Yt211b2Pt1etThis equation indicates that last month's sales and the current month's price are explanatory variables. The last term, et, is an error term.a.If the price of a portrait during month 21 is $10, what would you predict for sales in month 21?b.Does there appear to be a problem with autocorrela-tion of the residuals"