Question: What is the practical meaning of g'(55) = -0.54? There may be more than one option.
(a) When the car is going 55 mph, the rate of change of the fuel efficiency decreases to approximately 0.54 miles/gal.
(b) When the car is going 55 mph, the rate of change of the fuel efficiency decreases by approximately 0.54 miles/gal.
(c) If the car speeds up from 55 mph to 56 mph, then the fuel efficiency is approximately -0.54 miles per gallon.
(d) If the car speeds up from 55 mph to 56 mph, then the car becomes less fuel efficient by approximately 0.54 miles per gallon.