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A boy runs for 20 min.at a uniform speed of 18m/h.At what speed should he run for the next 40 min. So that the average speed comes 24km/hr |
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Answer» Given that, a boy runs for 20 MIN at a uniform speed of 18 km/h. Time = 20 min = 20/60 = 1/3 hours Speed = 18 km/hr We KNOW that, Distance = Speed × Time = 18 × 1/3 = 6 km We have to find that at what speed should he run for the NEXT 40 min. Now, New Time = 40 min = 40/60 = 2/3 hours New Speed = 24 km/hr Let us assume that the distance he travelled in 40 min be is x km. Total distance: x + 6 = 24, x = 24 - 6 = 18 km Also, assume that he require speed of y km/hr. Distance = Speed × Time → 18 = y × 2/3 → 18 × 3/2 = y → 9 × 3 = y → 27 = y Therefore, the speed of the boys is 27 km/hr. |
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