Vehicle weights The Minnesota Department of Transportation hoped that they could measure the weights of big trucks without actually stopping the vehicles by using a newly developed “weigh-in-motion” scale. After installation of the scale, a study was conducted to find out whether the scale’s readings correspond to the true weights of the trucks being monitored. In the Scatterplots, Association, and Correlation chapter, Exercise 50, you examined the scatterplot for the data they collected, finding the association to be approximately linear with R2 = 93%. Their regression equation is Wt = 10.85 + 0.64 Scale, where both the scale reading and the predicted weight of the truck are measured in thousands of pounds.
a) Estimate the weight of a truck if this scale read 31,200 pounds.
b) If that truck actually weighed 32,120 pounds, what was the residual?
c) If the scale reads 35,590 pounds, and the truck has a residual of -2440 pounds, how much does it actually weigh?
d) In general, do you expect estimates made using this equation to be reasonably accurate? Explain.
e) If the police plan to use this scale to issue tickets to trucks that appear to be overloaded, will negative or positive residuals be a greater problem? Explain.