Refer to the National Semiconductor study of manufactured silicon wafer integrated circuit chips, Exercise. Recall that the failure times of the microchips (in hours) were determined at different solder temperatures (degrees Centigrade). The data are repeated in the table below and saved in the WAFER file.

a. Fit the straight-line model E(y) = β0 + β1x to the data, where y = failure time and x = solder temperature.

b. Compute the residual for a microchip manufactured at a temperature of 152°C.

c. Plot the residuals against solder temperature (x). Do you detect a trend?

d. In Exercise, you determined that failure time (y) and solder temperature (x) were curvilinearly related. Does the residual plot, part c, support this conclusion?

Temperature (°C) Time to Failure (hours)

165 .............. 200

162 .............. 200

164 .............. 1,200

158 .............. 500

158 .............. 600

159 .............. 750

156 .............. 1,200

157 ..............1,500

152 .............. 500

147 .............. 500

149 .............. 1,100

149 .............. 1,150

142 .............. 3,500

142 .............. 3,600

143 .............. 3,650

133 .............. 4,200

132 .............. 4,800

132 .............. 5,000

134 .............. 5,200

134 .............. 5,400

125 .............. 8,300

123 .............. 9,700