A car travels 100 km at 50 km/h and then another 100 km at 25 km/h. What is its average speed for the whole trip?
Answer and explanation
Correct answer: D. 33,3333 km/h
- Step 1: Time for the first part = 100 ÷ 50 = 2 h; time for the second part = 100 ÷ 25 = 4 h.
- Step 2: Average speed = total distance ÷ total time = 200 ÷ 6 = 33,3333 km/h.
Answer
33,3333 km/h.
Why not the others: 37,5 km/h: the two speeds were averaged without weighting by time. 200 km/h: this is the total distance. 42,5 km/h: the simple average of the speeds.
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