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While traveling downstream a boat cover 154 km in 7 hours. If the speed of the stream is 4 km/h then find the time taken by boat to cover the same distance upstream.1. 11 hours2. 13 hours3. 9 hours4. 12 hours5. None of these |
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Answer» Correct Answer - Option 1 : 11 hours Given: Time take by boat to cover 154 km = 7 hours Speed of stream = 4 km/h Concept used: Upstream speed = Downstream speed – (2 × speed of stream) Calculation: Downstream speed of the boat = 154/7 ⇒ 22 km/h Upstream speed of boat = 22 – (2 × 4) ⇒ 22 – 8 ⇒ 14 km/h Time is taken by boat to cover the same distance upstream = 154/14 ⇒ 11 hours ∴ The time taken by boat to cover the same distance upstream is 11 hours. |
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