Civil engineers often use the straight-line equation, y Bo +B1x, to model the relationship between the mean shear strength of masonry joints and precompression stress, x. To test this theory, a series of stress tests were performed on solid bricks arranged in triplets and joined with mortar. The precompression stress was varied for each triplet and the ultimate shear load just before failure (called the shear strength) was recorded. The stress results for n 7 triplet tests is shown in the accompanying table followed by a printout of the regression analysis. Give a practical interpretation of the estimate of the slope of the least squares line. Round to three decimal places if needed.
Click the icon to view the table of results and the regression analysis
A. or every 1 ton increase in precompression stress, the shear strength of the joint is estimated to increase by 0.987 tons.
B. For a triplet test with a precompression stress of o tons, the shear strength of the joint is estimated to be 1.192 tons.
C. For a triplet test with a precompression stress of 1 ton, the shear strength of the joint is estimated to be 0.987 tons.
D. For every 0.987 ton increase in precompression stress, the shear strength of the joint is estimated to increase by 1 ton.

The engineers created a regression model to estimate the relationship between the "shear strength of masonry joints" (Y), measured in tons, and the "precompression stress" (X), measured in tons.

^Y= a + bXi

Using the regression output:

Estimate of the y-intercept: a= 1.192

Estimate of the slope: b= 0.987

In general terms you can interpret the slope as:

"Is the modification of the estimated mean of Y when X increases one unit"

In this case it means that every time the precompression stress increases one ton, the shear strength of the joint is estimated to increase 0.987 tons.

I hope this helps!