An article on estimating ZB-day strength of concrete considered regressing y = 28-day standard-cured strength (psi) againstx = accelerated strength (psi). Suppose the equation of the true regression line is y = 1,790 + 1.5x. (a) What is the expected value (in pounds per square inch) of 28-day strength when accelerated strength = 2,490 psi? : psi (b) By how much can we expect 28-day strength (in pounds per square inch) to change when accelerated strength increases by 1 psi? (c) By how much can we expect 28-day strength (in pounds per square inch) to change when accelerated strength increases by 130 psi? (d) By how much can we expect 28-day strength (in pounds per square inch) to change when accelerated strength decreases by 130 psi? E psi