Figure 123 shows a scatterplot that compares the distances and times for randomly selected Delta Air Lines flights de- parting from Hartsfield-Jackson International Airport in Atlanta, Georgia.

Let f(d) be the airborne time (in minutes) for a flight that traveled d miles.
a. By inspecting the scatterplot, determine which variable is being treated as the explanatory variable.
b. Describe the four characteristics of the association.
c. A reasonable model is f1d2 = 0.14d + 5.39. Determine the slope. Then find the reciprocal of the slope. Why is it an estimate of the mean speed of all the airplanes? Convert the units to miles per hour.
d. Use f to estimate the airborne time of Flight 833 from Atlanta to Albuquerque, New Mexico, which is a distance of 1267 miles.
e. The actual airborne time of Flight 833 was 179 minutes. Was the airplane€™s velocity a bit more or a bit less than your result in part (c)? Is the point that represents the flight a bit above or a bit below the graph of f? Explain.

Distance versus Time 350 300 250 200 150 100 50t 500 1000 1500 2000 2500 Distance (miles)