Question

A train travels of 300 km at a constant speed if the speed of the train is increased by 5 km/h the journey would have taken 2 hour less . Find the original speed of the train

Answer 1

Let the original speed of the train be x km/hr

Time when speed is x=300/x hours

Time when speed is x+5 km/hr =300/x+5

300/x-300/x+5= 2

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

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

2x^2+10x-1500=0

2(x^2+5x-750)=0

X^2+30x-25x-750=0

X(x+30)-25(x+30)=0

(X+30)(x-25)=0

X=25or -30

(-30 is rejected)

Actual speed =25km/hr