This question has several parts that must be completed sequentially. If you skip a part of the question, you will not receive any points for the skipped part, and you will not be able to come back to the skipped part. Tutorial Exercise An article on estimating 28-day strength of concrete considered regressing y = 28-day standard-cured strength (psi) against x = accelerated strength (psi). Suppose the equation of the true regression line is y = 1,780 + 1.2x. (a) What is the expected value of 28-day strength when accelerated strength = 2,420? (b) By how much can we expect 28-day strength to change when accelerated strength increases by 1 psi? (c) By how much can we expect 28-day strength to change when accelerated strength increases by 120 psi? (d) By how much can we expect 28-day strength to change when accelerated strength decreases by 120 psi