The accompanying data was extracted from the article “Effects of Cold and Warm Temperatu...

The accompanying data was extracted from the article “Effects of Cold and Warm Temperatures on Springback of Aluminum-Magnesium Alloy 5083-H111” (J. of Engr. Manuf., 2009: 427–431). The response variable is yield strength (MPa), and the predictor is temperature (°C).

Here is Minitab output from fitting the quadratic regression model (a graph in the cited paper suggests that the authors did this):

a. What proportion of observed variation in strength can be attributed to the model relationship?

b. Carry out a test of hypotheses at significance level .05 to decide if the quadratic predictor provides useful information over and above that provided by the linear predictor.

c. For a strength value of 100, . Estimate true average strength when temperature is 100, in a way that conveys information about precision and reliability.

d. Use the information in (c) to predict strength for a single observation to be made when temperature is 100, and do so in a way that conveys information about precision and reliability. Then compare this prediction to the estimate obtained in (c).