An aeronautical engineering student carried out an experiment to study how ratio related to the variables of a certain forward lifting surface relative to the main wing and placement relative to the main wing, obtaining the following data (Statistics for Engineering Problem Solving, p. 133):

a. Fitting the first-order model gives , whereas including as a predictor results in Calculate and interpret the coefficient of multiple determination for each model.

b. Carry out a test of model utility using for each of the models described in part (a). Does either result surprise you?