A boat goes 24 km downstream in 10 hours, it takes 2 hours more to cover the same distance against the stream. What is the speed of the boat in still water?
Correct answer: E. None of these
- A. 2km/hr
- B. 2.8 km/hr
- C. 4 km/hr
- D. 4.2 km/hr
- E. None of these
Explanation
The downstream speed is 24 km ÷ 10 hours = 2.4 km/hr, and the upstream journey takes 10 hours + 2 hours = 12 hours, giving an upstream speed of 24 km ÷ 12 hours = 2 km/hr. Therefore, the still-water speed is (2.4 km/hr + 2 km/hr) ÷ 2 = 2.2 km/hr, which is not among the options. Option a, 2 km/hr, is the upstream speed and not the still-water speed.
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