Slowing down in a curve: A study of average driver speed on rural highways by A. Taragin4 found a linear relationship between average speed S,in miles per hour, and the amount of curvature D, in...

Slowing down in a curve: A study of average driver speed on rural highways by A. Taragin4 found a linear relationship between average speed S,in miles per hour, and the amount of curvature D, in degrees, of the road. On a straight road (D = 0), the average speed was found to be 46.26 miles per hour. This was found to decrease by 0.746 mile per hour for each additional degree of curvature.

a. Find a linear formula relating speed to curvature.

b. Express using functional notation the speed for a road with a curvature of 10 degrees, and then calculate that value.