- A8 km/h
- B9 km/h
- C7.2 km/h
- D8.5 km/h
Step-by-Step Solution
Boat: 18 ÷ 12 = 1.5 h. Walk: 18 ÷ 6 = 3 h. Average = 36 ÷ 4.5 = 8 km/h. (9 km/h is the simple mean.)
Answer: A) 8 km/h
Ravi takes a boat 18 km downstream (10 km/h in still water, current 2 km/h) and then walks back along the bank at 6 km/h. What is his average speed for the whole 36 km?
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