Question

A train travels 360 km at uniform speed. If the speed had been 10 km/hr, it would have taken 3 hour less for the same journey. What is the speed of the train?

Answer 1

Answer:

Step-by-step explanation:

let the speed of train be x km/h

time taken = distance / speed= 360/x hr

second cond

increased speed = x+10 km/h

time taken = distance / speed= 360/x+10 hr

A.T.Q

360/x -360/x+10 = 3

360(1/x -1/x+10) =  3

360(10/x^2+10x)=3

3x^2+30x-3600=0

3(x^2 +10x - 1200)=0

x^2+10x-1200

now a=1 b= 2 c= -1200

D= b^2 - 4ac= (2)^2 - 4*1*-1200

4+4800=4804

x= 70.3 km/h