Question

a train travel a distance of 480km at a uniform speed.if the speed had been 8km/hr less,then it would have taken 3hr more to cover the same distance .we need to find the speed of train.

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)
=480/x-8 - 480/x= 3
=480(x-x+8)/x(x-8)=3
=480/3×8=x^2-8x
1280 = x2– 8x
x2– 8x – 1280 = 0
On solving we get x = 40
Thus the speed of train is 40 kmph

Answer 2

lets speed of train = s

a/c to question

【[s (s-8)] / 8】 ×3 = 480

s (s-8) = 160 ×8

s (s- 8 ) = 1280

by solving

s = 40 km/h


hope it helps