Question

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.
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Answer 1

Distance travelled by the train = 480 km

Let the speed of the train be x kmph

Time taken for the journey = 480/x

Given speed is decreased by 8 kmph

Hence the new speed of train = (x – 8) kmph

Time taken for the journey = 480/(x – 8)

Now we've got the equation:

480x/8 = 480x +3

This can be solved as follows.

1280 = x2 – 8x

x2 – 8x – 1280 = 0

On solving we get x = 40