Can Highway Builders Predict Pavement Strength Using Regression Lines?

[Integral0]

Concrete road pavement gains strength over time as it cures. Highway builders use regression lines to predict the strength after 28 days (when curving is complete) from measurements made after 7 days. Let x be strenth after 7 days (in pounds per square inch) and y the strength after 28 days.

y-hat = 1389 + .96x

Draw a graph of this line, with x running from 3000 to 4000 lbs per square inch.

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I don't know how to graph it because the words are confusing me . . . I labed my explanatory (x-axis) as psi from 3000 to 4000 lbs and the response variable (y-axis) as days. How do I graph 1389 (the intercept) on my graph if the y-axis is days?

 

[Integral0]

I solved it, thanks anyway

 

[tacman]

It seems like there may be some confusion with the information provided. The given regression line is predicting pavement strength, not days. The x-axis should represent the strength after 7 days (x) and the y-axis should represent the strength after 28 days (y). The intercept of 1389 would be plotted on the y-axis, as it represents the predicted strength after 28 days if there was no strength gained after 7 days. The line would then be drawn from the intercept with a slope of 0.96, indicating the expected increase in strength after 28 days for every 1 unit increase in strength after 7 days. It may also be helpful to label the graph as "Pavement Strength Prediction" or something similar.