Windchill Index The windchill index (revised in 2001) for a temperature of 32 degrees Fahrenheit and wind speed x miles per hour is W(x)=55.628−22.07x0.16.

a. Graph the windchill index on a graphing calculator using the window [0,50] by [0,40]. Then find the windchill index for wind speeds of x = 15 and x = 30 mph.
b. Notice from your graph that the windchill index has first derivative negative and second derivative positive. What does this mean about how successive 1-mph increases in wind speed affect the windchill index?
c. Verify your answer to part (b) by defining y2​ to be the derivative of 1​ (using NDERIV), evaluating it at x=15 and x=30,