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A man divided his journey into three parts of distances of 36 km, 40 km and 54 km. He travelled the distances at the speeds of 12 km/h, 10 km/h and 9 km/h respectively. What was his average speed during the entire journey?1. 20 km / hr2. 10 km / hr3. 13 km / hr4. 15 km / hr |
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Answer» Correct Answer - Option 2 : 10 km / hr Given: The man covers 36 km distance at the speed = 12 km/hr. He covers 40 km distance at the speed = 10 km/hr. He covers 54 km distance at the speed = 9 km/hr. Formula: Average speed = (Total distance/Total time) Calculation: Time taken by man to cover 36 km distance at the speed of 6 km/hr. = 36/12 = 3 hrs. Time taken by man to cover 40 km distance at the speed of 5 km/hr. = 40/10 = 4 hrs. Time taken by man to cover 54 km distance at the speed of 9 km/hr. = 54/9 = 6 hrs. Total distance = 36 + 40 + 54 = 130 km Total time = 3 + 4 + 6 = 13 hrs. ∴ Average speed = 130/13 = 10 km/hr. |
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