Question

a passenger train takes 2hours less for a journey of 300kilometre. If it's speed increased by 5kilometre/hour.Find it's original speed.

Answer 1

let the speed of train be x

then the time taken by train is 300/x

so (x+5)(300/x -2)=300

300-2x+1500/x-10=300

1500-2x^2/x=10

1500-2x^2-10x=0

2x^2+10x-1500=0

x^2+35x-20x-750=0

(x+35)(x-20)=0

x=20km/hr