At 12.00 hours Ravi starts to walk from his house at 8 kms an hour. At 13.30 hours, Shankar follows him from Ravi’s house on his bicycle at 12 kms per hour. When will Ravi be 6 kms behind Paul?

• (first notice that there is a mistake in question use shankar instead of paul or vice-versa)
  walking speed of Ravi= 8 km/h
  speed of shankar by bicycle= 12 km/h
  shankar starts cycling after 1 and 1/2 hour to that of Ravi
  distance travelled by Ravi in 1.5 hours = 1.5*8 = 12 km
  relative speed of ravi and shankar= 12-8 = 4 km/h
  according to question when shankar will lead Ravi by 6 km it means he will
  have to cover a total distance of (12 + 6) = 18 km.
  time taken to travell 18 km = 18/4 = 4.5 hours
  this time taken by shankar to travell 18 km after 13.30 hours
  so he will lead ravi = add(4 and 1/2 hours + 13 and 1/2 hours)
  =18 hours (ANSWER)
  
• 12 years agoHelpfull: Yes(26) No(4)
• ravi covers a distance of 12km when shanker is going to start his ride
  and shankar velocity 12kmph,where as ravi 8kmph..after 1.30 by trial and error consider the distance travelled by them in 2hr i.e ravi (12+16)=28km where as shankar 2*12=24km let us consider after 4.30hr ravi distance (12+36)=48km and shankar can cover 12*9/2=54km so the diff is 6km...so ravi will be 6km behind paul at 1.30+4.30=6p.m
• 12 years agoHelpfull: Yes(22) No(1)
• ravi after 3.00pm [3 hours] he covered distance ==24kms
  paul 1 min distance =12/60 ===>>1/5
  so after 1.30 min means 90 min he can covered 90(1/5)=18 kms
  paul after 3.00pm [1.30 hours ] he covered distance ==18.
  so exactely 3.00 pm ravi be 6 kms behind paul.
• 12 years agoHelpfull: Yes(6) No(11)
• ravi covers 1.5*8=12km in 1.5hrs i.e upto 13.30hrs...
  now paul has to cover 12+6=18km such that ravi will be will be 6km behind paul....but here as both are moving we have to take relative speed,so 18/(12-8) is the time taken i.e 4.5hrs means 4hrs 30mins and 13.30+4.30=18hrs is the ans...
  
• 12 years agoHelpfull: Yes(2) No(0)
• answer is 18/4=4.5
• 12 years agoHelpfull: Yes(1) No(6)