Q8 of 58 Page 118

A train travels 360 km at a uniform speed. If the speed had been 5 km/h more, it would have taken 1 hour less for the same journey. Find the speed of the train.

Let the speed of the train be x

Distance = 360 km


Time taken for a speed of x km/h


When speed is (x + 5) km/h time taken


According to the problem:



⇒ 360(x + 5) = 360x + x(x + 5)


⇒ x2 + 5x - 1800 = 0


Performing factorization we get:


x2 + 45x - 40x - 1800 = 0


⇒ x(x + 45) - 40(x + 45)


⇒ (x - 40)(x + 45) = 0


x = 40, - 45


Since Speed cannot be negative, so


Speed = 40 km/h


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