Aryan runs at a speed of 40 metre/minute. Rahul follows him after an interval of 5 minutes and runs at a speed of 50 metre/minute. Rahul's dog runs at a speed of 60 metre/minute and start along with Rahul. The dog reaches Aryan and then comes back to Rahul, and continues to do so till Rahul reaches Aryan. What is the total distance covered by the dog?

• 1200 mtrs
  
  Distance covered by Aryan in 5 mins = 40*5=200m
  Relative velocity of Rahul w.r.t Aryan = 10 mtr/min
  
  Time taken by Rahul to meet Aryan = 200/10 = 20 min
  
  Distance travelled by dog in 20 mins = 20* 60 = 1200 mtrs
• 12 years agoHelpfull: Yes(3) No(1)
• 1200meters = Total distance covered by the dog.
  
  Let X = Minutes
  And Y = Aryan runs speed = 40 meter per X
  And Z = Rahul runs speed = 50 meter per X (i.e., 200 + 50x)
  And D = Total distance covered by the dog = X* 60meters
  
  Y = Z
  40x = 200 + 50x
  200 = 10x
  x = 200/10
  x = 20
  
  So, by 20minutes, both Aryan and Rahul meets.(Rahul reaches Aryan.)
  
  So, dog covered distance, D = X * 60 meters = 20*60 = 1200 meters.
• 12 years agoHelpfull: Yes(2) No(1)
• 1200meters = Total distance covered by the dog.
  
  Let X = Minutes
  And Y = Aryan runs speed = 40 meter per X
  And Z = Rahul runs speed = 50 meter per X
  And D =Total distance covered by the dog = X* 60meters
  
  Note: Rahul starts in the interval of 5minutes from Aryan. On that time Aryan reach 5*40 = 200meters. So, Rahul starts = 200+50x
  
  40x = 200 + 50x
  200 = 10x
  x = 200/10
  x = 20
  
  So, by 20minutes, both Aryan and Rahul meets.(Rahul reaches Aryan.)
  
  So, dog covered distance, D = X * 60 meters = 20*60 = 1200 meters.
• 12 years agoHelpfull: Yes(1) No(1)