The following table presents the starting annual salaries (SAL) of a group of 30 college graduates who have recently entered the job market, along with their cumulative grade-point averages (CGPA).
a. Determine the least-squares estimates of the slope and intercept for the straight-line regression of SAL (Y) on CGPA (X).Draw the estimated line on the accompanying scatter diagram, and comment on the fit.
b. Are any of the assumptions for straight-line regression clearly not satisfied in this example?

c. Obtain a 95% confidence interval for β1.
d. Would you reject the null hypothesis H0: β1 = 4,000 at the α = .05 level?
e. Find and graph 95% confidence and prediction bands.
f. Would you reject the hypothesis H0: µY|X = 11,500 at X0 = 2.75?

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SAL (Y) CGPA (X) SAL (r) CGPA (X) 10455 2.58 9680 7300 9388 2.52 12496 3.22 11812 3.37 9224 11725 11320 12000 12500 3.5s 13310 3.64 12105 3.72 8000 12548 7700 10028 2.30 2.83 2.37 2.52 3.22 3.55 3.55 2.47 2.47 2.31 2.47 13255 13004 8000 2.43 3.08 2.78 2.98 10750 278 2.78 12322 2.98 2.58 2.58 2.58 11669 6200 224 11522 11002 10666 10839 2.70 SAL (Y), thousands of dollars 90