As concrete cures, it gains strength. The following data represent the 7-day and 28-day strength (in pounds per square inch) of a certain type of concrete:

(a) Treating the 7-day strength as the explanatory variable, x, determine the estimates of ß0 and ß1.
(b) Compute the standard error of the estimate.
(c) Determine Sb1.
(d) Assuming the residuals are normally distributed, test whether a linear relation exists between 7-day strength and 28-day strength at the α = 0.05 level of significance.
(e) Assuming the residuals are normally distributed, construct a 95% confidence interval for the slope of the true leastsquares regression line.
(f) What is the estimated mean 28-day strength of this concrete if the 7-day strength is 3000 psi?