Let x be a random variable that represents blood glucose level after a 12-hour fast. Let y be a random variable representing blood glucose level 1 hour after drinking sugar water (after the 12-hour fast). Units are in milligrams per 10 milliliters (mg/10 ml). A random sample of eight adults gave the following information.

(a) Draw a scatter diagram for the data.
(b) Find the equation of the least-squares line and graph it on the scatter diagram.
(c) Find the sample correlation coefficient r and the sample coefficient of determination r2. Explain the meaning of r2 in the context of the application.
(d) If x = 9.0, use the least-squares line to predict y. Find an 80% confidence interval for your prediction.
(e) Use level of significance 1% and test the claim that the population correlation coefficient r is not zero. Interpret the results.
(f) Find an 85% confidence interval for the slope b of the population-based least-squares line. Explain its meaning in the context of the application.

XI 6.2 8.4 7.0 7.5 8.1 6.9 10.0 9.7 19.8 10.7 10.3 11.9 14.2 7.0 14.6 12.2