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Amit covers from A to B and back to A by train in 16 hour. If the ratio of speed from A to B and back from B to A is 5 : 3. Find the speed of the train in the onward journey from A to B if the distance between A and B is 300 kilometres.1. 50 km/hr2. 30 km/hr3. 25 km/hr4. 45 km/hr5. 15 km/hr |
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Answer» Correct Answer - Option 1 : 50 km/hr Given: Total time = 16 hours Total distance = 600 km The ratio of speed of onward journey and return journey is 5 : 3 . Formula used : Average speed = Total distance/Total time taken Average speed = 2 x y/x + y Where, x and y are speeds of onward journey and return journey respectively . Calculations : Let speed of onward journey and return journey be 5x and 3x respectively. Average speed = 600/16 ----(1) Also, Average speed = 2 × 5x × 3x/(5x +3x) ----(2) On equating equation (1) and (2) we get , ⇒ 2 × 5x × 3x/(5x +3x) = 600/16 ⇒ 30x2/8x = 600/16 ⇒ x = 10 ⇒ speed of onward journey is 5x = 5 × 10 = 50 km/hr ∴ The speed of train in onward journey from A to B is 50 km/hr. |
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