A forester has a unique ability to estimate the volume (in cubic feet) of trees prior to a timber sale. The timber company that employs the forester wants him to train other employees in his technique of estimation. After a training period, the forester randomly selects 25 trees that will be cut down for processing. The forester€™s assistant estimates the cubic- foot volume of each tree. After the tree has been chopped down, the forester obtains its actual cubic- foot volume.

a. Plot the data in a scatterplot. Does there appear to be a reasonable relation between the estimated and actual volumes?
b. Fit a regression model relating the estimated volume to the actual volume.
c. If the assistant is producing very accurate estimates of the volume, what should be the value of the slope of the regression line?
d. Is there significant evidence that the assistant is producing accurate estimates of the volume of the trees?

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Estimated volume 111 13.0 12.0 112 122 13.0 12.5 16.2 14.4 154 15.9 16.4 15.5 Actual volume 114 12.5 13.1 133 13.7 13.8 14.3 15.9 16.4 17.0 18.8 188 19.2 Estimated volume 169 176 158 16.4 187 189 19.7 19.7 210 19.0 21.5 21.3 Actual volume 19.7 19.8 19.8 20.1 20.1 20.9 224 22.7 23.1 233 24.0 248