Q. n a 100 m race, A runs at 8km per hour. If A gives B a start of 4 m and still him by 15 seconds, what is the speed of B?

• A's speed = (8*(5/18)= 20/9 m/sec
  time taken by A to cover 100m = 100*(9/20) = 45 sec
  so time taken by B to cover 96m =(45+15) =60sec
  
  so B's speed is ((96/60)*(18/5)) kmph = 5.76 kmph
• 11 years agoHelpfull: Yes(45) No(1)
• time taken by A to complete 100m = (100*60*60/8*1000)=45sec
  A beats B by 15 sec which means B completes 100m in 60 sec.
  therefore speed of B is= 96/60= 1.6m/sec.
  
• 10 years agoHelpfull: Yes(3) No(0)
• A speed is 8kmph= 20/9 mts/sec.
  and A gave B a 4m start so A has to cover 100mts and B covers only 96mts.
  A won by 15 sec.
  Hence time= distance/velocity
  A takes less time . therfore
  B's Time - A's Time =15sec
  now 96/B-100/(20/9)=15. solving it we get B= 96/60 mts/sec.
  so B speed is 72/25 kmph
• 11 years agoHelpfull: Yes(2) No(0)