The speed of an express train is x km/h and the speed of a ordinary train is 12 km/h less than that of express train. If the ordinary train takes 1 hr longer than the express train to cover a distance of 240 km find the speed of the express train.

• let express speed be "v" and time be "t"
  And so the speed of passenger is "v-12" and time taken is "1+t"
  as the distance traveled is same for both trains,equate distance of both trains
  1) for express distance
  (240)=v*t
  v=240/t------------
  
  2) for passenger distance(240)=(v-12)*(t+1)
  use in (2)
  (240/t)-12=(240/(1+t))
  rearranging we get quadratic equation
  240t=240+240t-12t-12t(square)
  solving we get "t" value as 4
  
  3) and use value of t in
  answer is speed of express is 60km/hr
  
  
  
  
  
  
• 11 years agoHelpfull: Yes(0) No(0)
• distance is same for both the trains
  given that speed of ordinary is x-12
  we can say that difference between time taken by both the trains is 1 hr
  240/(x-12) -240/x = 1
  by solving this x=60kmhr
• 11 years agoHelpfull: Yes(0) No(0)
• 60 km/h
  If speed(km/h) of an express train =x & ordinary train=x-12
  then [240/(x-12)- 240/x ]=1
  x^2-12x-2880=0 or (x-60)(x+48)=0, x=60 km/h
• 11 years agoHelpfull: Yes(0) No(0)