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23.
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A boat running upstream takes 8 hours 48 minutes
to cover a certain distance, while it take 4 hours to cover the same distance
running downstream. What is the ratio between the speed of the boat and speed
of the water current respectively?
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A. 1:3
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B. 3:8
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C. 6:3
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D. 8:3
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Answer:
D.
Explanation:
Let
the man rate upstream be x kmph and that downstream be y kmph. Then,
Distance
coverd upstream in 8 hrs 48 min. = Distance coverd downstream in 4 hrs.
⇒ [x 8 4/5] = (y * 4) ⇒ 44/5 x = 4y ⇒ y = 11/5 x.
∴ Required ratio = [y + x / 2] : [6x /
5 * 1/2] : [6x / 5 * 1/2]
=
8/5 : 3/5 = 8:3.
