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The ratio of average speed of onward to the average speed of return journey is 7 ∶ 5. If the time taken in the whole journey of 490 km is 24 hours. Find the speed of train in onward journey?1. 34.5 km / hr2. 24.5 km / hr3. 12.5 km / hr4. 45.5 km / hr5. 15.5 km / hr |
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Answer» Correct Answer - Option 2 : 24.5 km / hr Given∶ The ratio of average speed of onward to the the average speed of return journey is 7 ∶ 5. The time taken in the whole journey of 490 km is 24 hours. Formula used∶ Average speed = 2 x × y / (x + y) Calculations∶ Let the average speed of the onward journey be x Let the average speed of the return journey be y Average speed = 2 x × y / (x + y) According to the question∶ average speed of the onward journey 7x average speed of the return journey 5x Average speed = (2 × 7x × 5x) / (7x + 5x) = 490 / 24 ⇒ x = 3.5 The average speed of the onward journey, 7x = 7 × 3.5 ⇒ 24.5 km / hr |
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