A train travels 360 km at a uniform speed. If the speed had been 5 km/hr more, it would have taken 4 hour less for the same journey. Form the quadratic equation to find the speed of the train.

Question

Philoid · Accepted Answer

Let the speed of the train be ‘a’ km/hr and the actual time taken be ‘t’

Given, train travels 360 km at a uniform speed. If the speed had been 5 km/hr more, it would have taken 4 hour less for the same journey.

Distance = speed × time

⇒ 360 = a × t

⇒ t = 360/a

Also, 360 = (a + 5)(t – 4)

⇒ 360a = (a + 5)(360 – 4a)

⇒ 360a = 360a + 1800 – 4a² – 20a

⇒ a² + 5a – 450 = 0