A train travels 2.5 hours at 60 km/h and then 1.5 hours at 80 km/h. What is its average speed for the whole trip?
Answer and explanation
Correct answer: B. 67.5 km/h
- Step 1: The distances are km and km, in total km. Step 2. The total time is 4 hours, so the average speed is . Answer: 67.5 km/h. Why not the others: 70 is the plain mean of the speeds, and 65 and 72 have no basis in the total distance and time.
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