Q. In a 100 m race A runs at 8km per hour. If A give B a start of 4 m and still him by 15sec. What is the speed of B?

• A gives B a start of 4m.. so, A runs 100m and B runs 96m to complete the race..
  so, the time taken by A to complete race is 100/(8*5/18)=45sec
  Given, A beats B by 15sec.. so, B took (45+15)=60sec to complete race...
  so, the speed of B is (96/60)*(18/5)=5.76km/hr
• 11 years agoHelpfull: Yes(56) No(0)
• ans:
  speed of A = 8km/hour =8000/3600=20/9 m/sec
  time taken by A to complete race = 100*9/20 = 45 sec
  now,
  as B take 15sec more to complete race so total time taken will be 45+ 15=60 sec
  
  distance covered byB is 100-4=96m
  so speed of B = 96/60 = 1.6 m/sec = 5.76 km/hour
• 11 years agoHelpfull: Yes(11) No(0)
• a's time=(100*18)/(8*5)=45s.
  b's tme=45+15=60s.
  b's speed=(96*18)/(60*5)=5.76km/hr
• 11 years agoHelpfull: Yes(3) No(0)
• A runs 100m and B runs 96 m..
  The time taken by A complete the race is 100(8000/3600)=45secs.
  Given that A beats B with 15 seconds.. So The distance taken to complete the race is=60s (45+15)..
  
  The speed of B=(96/60)(3600/1000)=5.76km/hr.
• 11 years agoHelpfull: Yes(2) No(0)
• speed of B= 96/15 meter/sec..or (96/15)*18/5 km/hr......
• 11 years agoHelpfull: Yes(1) No(3)