Question

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.

Answer 1

The distance travelled = 360 km. 

Let the speed of the train = x kmph. 

Time taken to complete a journey = \(\frac{distance}{speed}\)

⇒ x² + 5x = 1800 

⇒ x² + 5x – 1800 = 0 

⇒ x² + 45x – 40x – 1800 = 0

⇒ x(x + 45) – 40(x + 45) = 0 

⇒ (x + 45) (x – 40) = 0 

x + 45 = 0 or x -40 = 0 

x = -45 or x = +40 

But x can’t be negative. 

∴ The speed of the train = 40 kmph.