(Q) A train travels a distance of 480 km at a uniform speed. If the speed had been 8 km / h less, then it would have taken 3 hours more to cover the same distance. We need to find the speed of the train.

Ans:  Let’s the speed of the train be km /h

We know that the time taken  =

Since the distance is 480 km, hence the time =

In 2nd case, speed will be km / h and the time taken to cover same distance of 480 km will be

By given condition, in 2nd case, time taken is 3 hrs more i.e.

Time taken in 2nd case = Time taken in 1st case + 3

Here, we reject x = – 32 because the value of the train’s speed can not be a negative number.

Therefore, speed of the train x = 40 km/ h

Hence, the speed of the train is 40 km/ h.

Check:

If train speed is 40 km/h, time taken to cover 480 kms = = 12 hrs

In 2nd case, speed is 8 km/h less, i.e. 40 – 8 = 32 km/h

Hence time taken to cover 480 kms = = 15 hrs

Since, time in 2nd case is 3 hrs more than the 1st one – it meets the given condition, hence our answer is correct. 

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