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58.
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A boat takes 19 hours for travelling downstream
fro poin A to point B and coming back to a point C midway between A and B. If
the velocity of the stream is 4 kmph and the speed of the boat in still water
is 14 kmph, what is the distance between A and B?
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A. 180 km
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B. 190 km
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C. 220 km
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D. 230 km
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Answer:
A.
Explanation:
Speed
downstream = (14 + 4) km/hr = 18 km/hr;
Speed
upstream = (14 - 4) km/hr = 10 km/hr.
Let
the distance between A and B be x km. Then,
x/18
+ (x/2)/10 = 19 ⇔ x/18 + x/20 = 19 ⇒ x = 180 km.
