=+31. Secretary performance. The AFL-CIO has undertaken a study of 30 secretaries’ yearly salaries (in thousands of dollars). The organization wants to predict salaries from several other variables. The variables to be considered potential predictors of salary are:

X1 = months of service X2 = years of education X3 = score on standardized test X4 = words per minute (wpm) typing speed X5 = ability to take dictation in words per minute