Answer
Prediction in part (a) was made to find the confidence interval for the mean 28-day strength of all concrete whose 7-day strength is 2550 psi.
Prediction in part (c) was made to predict the interval of the 28-day strength of a concrete whose 7-day strength is 2550 psi. The interval obtained is the same for any concrete whose 7-day strength is 2550 psi.
Work Step by Step
Given above.
