Pia and Ria start running simultaneously from the same point on a
circular track of length 4200 m. If they run in opposite directions,
they meet for the first time exactly after 2 minutes from the start and
they meet at seven distinct points on the track. If they run in the same
direction, they meet at three distinct points on the track. How much
time (in minutes) does Ria take to complete one round, if she is the
slower runner?

1) 7 mins
2) 6 mins
3) 5 mins
4) 2 mins

• Let speed of Riya is R and Piya is P....since its given that P>R
  
  P-R=3(Distinct point when they run in same direction is diff of speeds)
  P+R=7(Distinct points when they run in opp. direction is sum of speeds)
  Solving gives p=5 and R=2
  
  P=5x and R=2x are the speeds.
  
  4200/(5x+2x)=120 (They meet after 120 sec when travelling in opp direction)(given)
  
  x =5
  
  speed are 25m/s and 10m/s.
  
  Time by Riya=4200/10= 420 sec=7 min
• 4 years agoHelpfull: Yes(0) No(0)