Quantitative Aptitude • Time, Speed & WorkMedium
A cyclist goes from one town to another at 60 km/h and comes back by the same road at 90 km/h. What is the average speed for the whole journey?
A. 75 km/h
B. 30 km/h
C. 72 km/h✓ Correct Answer
D. 77 km/h
💡 Solution & Explanation
Average speed = total distance ÷ total time, not the average of the two speeds. For equal distances, average speed = 2ab ÷ (a + b) = 2 × 60 × 90 ÷ (60 + 90) = 72 km/h. The simple average (75 km/h) is wrong because more time is spent at the slower speed.
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