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The speed of a boat in still water is 6 kmph and the speed of the stream is 1.5 kmph. A man rows to a place at a distance of 22.5 km and comes back to the starting point. The total time taken by him is :
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- 10 hours
- 4 hours 10 minutes
- 6 hours 10 minutes
- 8 hours
- 10 hours
Correct Option: D
Given in question , speed of a boat in still water = 6 kmph and the speed of the stream = 1.5 kmph
Rate downstream = (6 + 1.5) kmph = 7.5 kmph
Rate upstream = (6 – 1.5) kmph = 4.5 kmph
Distance = 22.5 km
According to the question,
| Time = | |
| Speed |
| ∴ Required time = | + | ||
| 7.5 | 4.5 |
Required time = 3 + 5 = 8 hours.
