As concrete cures, it gains strength. The following data represent the 7-day and 28-day strength in pounds per square inch (psi) of a certain type of concrete. Complete parts (a) through (b) below. (a) A normal probability plot suggests that the residuals are normally distributed. Test whether a linear relation exists between 7-day strength and 28-day strength at the a = 0.05 level of
significance. Determine the P-value of this hypothesis test. See picture for data.
