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A boat which has a speed of 5 km/hr in still water covers 1km upstream path in 15 minutes. How much distance it could cover in 1 hour 45 minutes in downstream?1). 72). 33). 44). 10.5 |
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Answer» Speed of water in STILL water = ½ × (speed downstream + speed upstrem) Speed upstream = 1/(15 / 60) = 4 Let distance covered in downstream be n km Time REQUIRED = 1 + 45/60 = 7/4 Speed downstream = n/(7/4) = 4n/7 Speed of water in still water = 5 ⇒ 5 = ½ × (4n/7 + 4) ⇒ 10 = (4n + 28)/7 ⇒ 70 = 4n + 28 ⇒ 4n = 42 ⇒ n = 10.5km ⇒ 10.5 km will be covered in downstream. |
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