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63.
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A man can row at 5 kmph in still water. If the
velocity of current is 1 kmph and it takes him 1 hour to row to a plce and
come back, how far is the place?
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A. 2 km
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B. 2.4 km
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C. 2.5 km
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D. 3.4 km
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Answer:
B.
Explanation:
Speed
downstream = (5+1) kmph = 6 kmph; Speed upstream = (5 - 1)kmph = 4 kmph. Let
the required distance be x km.
Then,
x/6 + x/4 = 1 ⇔ 2x + 3x = 12 ⇔ 5x = 12 ⇔ x = 2.4 km.
