LetYtbe the sales during montht(in thousands of dollars) for a photography studio, and letPtbe the price charged for portraits during montht. The data are in the fileP11_45.xlsx. Use regression to fit the following model to these data:Yt = a + b1Ytˆ’1 + b2Pt + etThis equation indicates that last month’s sales and the current month’s price are explanatory variables. The last term, et, is an error term.If the price of a portrait during month 21 is $10, what would you predict for sales in month 21?Does there appear to be a problem with autocorrelation of the residual? Explain your answer.