A boat goes 20 km downstream in 1 hour and 20 km upstream in 2 hours. What is the speed of the boat in still water?
A12 km/h
B15 km/h
C18 km/h
D20 km/h
Explanation
Downstream speed = 20 / 1 = 20 km/h. Upstream speed = 20 / 2 = 10 km/h. Speed of boat in still water = 0.5 * (20 + 10) = 15 km/h.
Exam Relevance
- Topic: Speed, Time & Distance
- Subtopic: Boats and Streams
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