Brightness (%): 54 61 65 100 100 100 50 57 54 Contrast (%): 56 80 70 50 65 80 25 35 26 Useful range (ng): 96 50 50 112 96 80 155 144 255 Round your answers to 4 significant digits. (a) Fit a multiple linear regression model to these data. y = + )x1+ ( )x2, where X1 = %brightness, X2 = %contrast. (b) Estimate o2. (c) Compute the standard errors of the regression coefficients. se ( Bo) = i se ( B 1) = i se ( B 2 ) = i (d) Predict the useful range when brightness = 76 and contrast = 71. y =