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Two boats P and Q travels downstream from A to B. The ratio of time taken to cover the distance from A to B by both boat is 4 : 5. If speed of boat Q is 34 km/h and speed of stream is 6 km/h, what will be the speed of boat P, when it travel from B to A?1. 40 km/h2. 50 km/h3. 44 km/h4. 38 km/h5. None of these |
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Answer» Correct Answer - Option 4 : 38 km/h Given: The ratio of time taken to cover the distance from A to B by both boats is 4 : 5 The speed of boat Q is 34 km/h Concept: When distance is constant The ratio of speed is equal to inverse the ratio of time. Hence, if the ratio of the speed of A : B is 4 : 5, the ratio of time taken by A and B would be 5 : 4. Calculation: Let the speed of boat P be x km/h. According to the question The speed of boat P downstream is (x + 6) km/h The speed of boat Q in downstream is (34 + 6) = 40 km/h Now, The ratio of the speed of boat P and Q is ⇒ (x + 6) : 40 = 5 : 4 ⇒ x + 6 = 50 ⇒ x = 44 km/h So, The speed of boat P, when It travels from B to A (upstream) ⇒ 44 - 6 ⇒ 38 km/h ∴ 38 km/h |
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