A car goes from Town A to Town B at 60 km/h and returns along the same road at 40 km/h. What is its average speed for the whole trip?
Correct answer: D. 48 km/h
Take a distance of 120 km each way: going takes 2 hours and returning takes 3 hours. Average speed = 240 km ÷ 5 h = 48 km/h, not the simple average of 50, because more time is spent at the slower speed.
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