Tractor rollover protection. In agriculture, a main cause of fatal injuries is tractor rollover. To combat this problem, tractor manufacturers have installed foldable rollover protection structures (FROPS). Human Factors (February 2020) published a study on the incorrect usage of FROPS. A sample of 20 farmers were recruited to drive tractors with FROPS installed. One common problem is incorrectly setting the vertical distance from the FROPS pivot pin to the top of the FROPS when in an upright position. This distance (in millimeters) was recorded for each of the 20 farmers as well as the farmer’s working experience (in years). The data (simulated from information provided by the study) are listed in the accompanying table.

a. Fit a simple linear regression model relating FROPS pivot pin-top distance (y) to farmer’s working experience (x). Give the least squares prediction equation.

b. Practically interpret the estimated y-intercept and slope of the model, part

a. c. Predict the pivot pin-top distance set by a farmer with 25 years of experience. Farmer Exp (years) Distance (mm) 1 22 527 2 47 553 3 17 485 4 9 596 5 1 354 6 20 713 7 1 736 8 18 762 9 28 596 10 1 381 11 7 374 12 41 518 13 18 855 14 9 404 15 26 654 16 16 683 17 53 774 18 49 823 19 35 426 20 24 440 Applying the Concepts—Intermediate