In a 4000 meter race around a circular stadium having a circumference of 1000 meters, the fastest runner and the slowest runner reach the same point at the end of the 5th minute, for the first time after the start of the race. All the runners have the same staring point and each runner maintains a uniform speed throughout the race. If the fastest runner runs at twice the speed of the slowest runner, what is the time taken by the fastest runner to finish the race?

• 10 minutes
  
  If the fastest runner runs at twice the speed of the slowest runner, they will meet only when fastest runner has covered one round extra as compared to slowest runner.
  So fastest runner covered 2 rounds and slowest runner covered one round of 1000 m in 5 min.
  
  so fastest runner will complete race of 4000 m in 2*5= 10 minutes.
• 12 years agoHelpfull: Yes(8) No(3)
• 10minutes.
  Ratio of the speeds of the fastest and the slowest runners is = 2 : 1.
  Hence they should meet at only one point on the circumference i.e. the starting point (As the difference in the ratio in reduced form is 1).
  For the two of them to meet for the first time, the faster should have completed one complete round over the slower one. Since the two of them meet for the first time after 5 min,
  the faster one should have completed 2 rounds (i.e. 2000 m) and
  the slower one should have completed 1 round. (i.e. 1000 m) in this time.
  Thus, the faster one would complete the race (i.e. 4000 m) in 10 min.
• 12 years agoHelpfull: Yes(2) No(2)
• fastest runner will finish the race in 10 mins.
• 12 years agoHelpfull: Yes(2) No(0)
• 10 mins
  
  
  
  In 5 mins,
  the faster one have completed 2 rounds (i.e. 2000 m) and
  the slower one have completed 1 round. (i.e. 1000 m) in this time.
  
  so the faster one will complete 4 rounds (i.e. 4000 m) in 10 minutes
• 12 years agoHelpfull: Yes(2) No(0)
• Slowest and fastest runners starts at the same position . so they will cross each other , but it is not considered .
  After that next time they will cross each other at starting point .
  means slower = 1000m so speed = 1000/5 = 200m/min
  & faster = 2000m so speed = 2000/5 = 400 m/min
  but fastest runner already run at twice speed .
  so he take 5 min to cover 2000m and will take 10 min to complete race.
  
• 12 years agoHelpfull: Yes(0) No(2)