Q. A train travels 360 km at a uniform speed. If the seed had been 5 km/h more, it would have taken 1 jour less for the same journey. Find the speed of the train.
Ans: Let take the speed of the train be x km/h.
We know that the time ‘T’ taken to cover a distance ‘D’ by an object moving at a speed ‘S’ is given by:
T =
Hence, Time taken to cover distance 360 km at a speed of x km/h will be:
Next, if Speed becomes (x + 5) km/h, Time taken will be:
by given condition,
Therefore, x = – 45 and x = 40
Here, we reject x = – 45 because speed can not be negative.
Only x = 40 is accepted.
Hence, speed of the train is 40 km/h.
Check:
If speed is 40 km/h, it will take hrs.
When speed is increased by 5 km/h, new speed is 45 km/h,
here, new time will be hrs
Since this is 1 hr less than earlier time, hence our answer is correct.
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