Representative data on x carbonation depth (in

Chapter 0, Problem 5.25

(choose chapter or problem)

Representative data on x carbonation depth (in millimeters) and y strength (in megapascals) for a sample of concrete core specimens taken from a particular building were read from a plot in the article The Carbonation of Concrete Structures in the Tropical Environment of Singapore (Magazine of Concrete Research [1996]: 293300): Depth, x 8.0 20.0 20.0 30.0 35.0 Strength, y 22.8 17.1 21.1 16.1 13.4 Depth, x 40.0 50.0 55.0 65.0 Strength, y 12.4 11.4 9.7 6.8 a. Construct a scatterplot. Does the relationship between carbonation depth and strength appear to be linear? b. Find the equation of the least-squares line. c. What would you predict for strength when carbonation depth is 25 mm? d. Explain why it would not be reasonable to use the least-squares line to predict strength when carbonation depth is 100 mm.