Question

On a 200 km track, a train travels the first 60 km at a uniform speed of 40 km/h. How fast must the train travel the rest of the distance so as its average will be 80 km/h for the entire trip?​

Answer 1

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Now, it is given that, the speed of the train for the first 60 km is 40 km/h.

• We know that, Time = Distance / Speed.

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Therefore,—

Time is taken by the train to cover first 60 km = 60/40 = 1.5 Hours

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Total time Should be taken by the train to cover 200 km = 200/80 = 2.5 Hours

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Therefore, time remaining for the train to cover next 140 Km

• = 2.5 – 1.5
• = 1 Hour

Hence, The Train have to Cover 140 Km in 1 Hour,

Now, Required Speed = Distance / Time

• = 140/1
• = 140 Km/h

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Therefore, the train has to travel at the speed of 140 Km/h.