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The train covered 8.7 km at the speed of 6 km/hr, stopped for 6 minutes and then covered 12.5 km at the speed of 5 km/hr. Find the average speed of train during the whole journey.1. 9.23 km/hr2. 5.23 km/hr3. 6 km/hr4. 10 km/hr |
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Answer» Correct Answer - Option 2 : 5.23 km/hr Given: The train covered 8.7 km at the speed of 6 km/hr, stopped for 6 minutes and then covered 12.5 km at the speed of 5 km/hr. Concepts used: Time = Distance/Speed Average speed = Total distance/total time Calculation: Time taken by train to cover 8.7 km = 8.7/6 = 1.45 hours Time taken by train to cover 12.5 km = 12.5/5 = 2.5 hours. Stoppage time = 6 minutes = 6/60 hour = 0.1 hour Total distance = 8.7 km + 12.5 km = 21.2 km Total time = 1.45 + 0.1 + 2.5 = 4.05 hours Average speed = Total distance/total time Average speed = 21.2/4.05 = 5.23 km/hr ∴ Average speed of train is 5.23 km/hr. |
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