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A person can row a boat d km upstream and the same distance downstream
in 5 1 hrs Also he can row the boat 2d km upstream in 7 hours. He will row the 4
same distance downstream in
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3 1 hrs 2 -
3 1 hrs 4 -
4 1 hrs 4 - 4 hours
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Correct Option: A
Given that , Distance = d km
Let the speed of boat in still water be p kmph and that of current by q kmph.
According to the question,
| ∴ | + | = | .........(i) | |||
| p + q | p - q | 4 |
| and | = 7 ⇒ | = | .........(ii) | |||
| p - q | p - q | 2 |
By equation (ii) – (i),
| ⇒ | = | - | = | = | |||||
| p + q | 4 | 2 | 4 | 4 |
| ⇒ | = | = 3 | hours. | |||
| p + q | 2 | 2 |
