A car travels 120 km in 2 hours and then 90 km in 1 hour. What is its average speed for the whole journey?
Answer and explanation
Correct answer: C. 70 km/h
- Step 1: Total distance = 120 + 90 = 210 km. Step 2. Total time = 2 + 1 = 3 hours, so speed = 210 / 3 = 70. Answer: 70 km/h. Why not the others: 75 averages the speeds, which ignores the different times; 105 divides by 2 stages; 90 is only the second stage.
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