A car travels from city A to city B at a speed of 40 mph and returns at a speed of 60 mph. What is the average speed of the car for the entire trip?
Correct: C
The average speed for a round trip is calculated using the formula: Average Speed = (2 * speed1 * speed2) / (speed1 + speed2), where speed1 and speed2 are the speeds for the two parts of the trip. Substituting the given speeds, we get Average Speed = (2 * 40 * 60) / (40 + 60) = (4800) / (100) = 48 mph.