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A car travels at a speed of 80 km/h during the first half of its running time and at 40 km/h during the other half. Find the average speed of the car. |
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Answer» Let the total running time = x hrs Speed in the first half of its running time i.e., x/2 hrs = 80 km/h ∴ Distance covered in x/2 hrs = 80 x (x/2) =80x/2 = 40x km Speed in second half its running time = 40 km/h ∴ Distance covered in x/2 hrs = 40 x (x/2) = 20x km Total distance = 40x + 20x = 60x km Total time = x/2 + x/2 = x hrs ∴ Average speed = Total distance /Time = 60x/x =60 km/hr |
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