An economist wanted to investigate the factors that determined the price of petrol RON97. He gathered 17 months of data on the four variables below: Y = Price of petrol RON97 (RM/litre) X1 = Price of...

Extracted text: An economist wanted to investigate the factors that determined the price of petrol RON97. He gathered 17 months of data on the four variables below: Y = Price of petrol RON97 (RM/litre) X1 = Price of world oil (USD/barrel) X2 = Exchange rate (RM/USD) X3 = Quantity demand for petrol RON97 (million litre) The Excel results are shown as follows: ANOVA df SS MS Significance F Regression Residual 0.467 0.062 3 0.156 32.763 0.000 13 0.005 Total 16 0.529 Coefficients Standard Error t Stat P-value 0.094 0.000 0.003 Intercept -1.132 0.627 -1.805 X1 0.021 0.003 7.000 X2 -0.334 0.092 -3.630 X3 0.010 0.007 1.429 0.165 (a) Determine the regression equation. (b) Determine the coefficient of determination, and interpret. (c) Which independent variables linearly related to the price of petrol RON 95 in this model? Explain. (d) Is the model valid? Explain.