The following estimated regression equation relating sales to inventory investment and advertising expenditures was given. y = 26 + 15x1 + 8x2 The data used to develop the model came from a survey of 10 stores; for those data, SST = 19,000 and SSR = 14,440. (a) For the estimated regression equation given, compute R? R2 = (b) Compute Ra. (Round your answer to two decimal places.) R (c) Does the model appear to explain a large amount of variability in the data? Explain. (For purposes of this exercise, consider an amount large if it is at least 55%. Round your answer to the nearest integer.) The adjusted coefficient of determination shows that do of the variability has been explained by the two independent variables; thus, we conclude that the model -Select-| explain a large amount of variability