61.A
man can row 6 kmph is still water. If the river is running at 1 kmph it takes
90 min to row to a place and back. How far is the place?
[A]
410
[C]
490
[B]
415
[D]
480
Answer : [B]
Explanation :
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Speed
downstream = (6 + 1) kmph = 7 kmph
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Speed
upstream = (6 – 1) kmph = 5 kmph
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Then
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x
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+
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x
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=
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90
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(or)
5x + 7x =
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90 x 35
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;
(or) x = 4.375 km
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7
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5
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60
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60
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