the speed of express of train is xkm/hr and the speed of ordinary train is 12 km\hr less than that of the express train.if the odrinary train takes one hour longer than the express train to cover a distance of 240km find the speed of express train

Asked by ushanihar12 | 6th Feb, 2019, 10:07: PM

Expert Answer:

Let x be the speed of express train
speed of slower train = x-12
travel time = distance / speed

[240/(x-12)] -[240/x] =1

Least Common Divisor of the above fractions is
x(x-12)

240x - 240x + 2880=x2 - 12x
x2 -12x - 2880 = 0
(x+48)(x-60)=0
x = - 48 or x = 60
 
As speed cannot be negative, we discard the result x= -48.

Therefore, speed of the express train is 60 km/hr


Answered by Science Mate | 7th Feb, 2019, 12:21: AM