Q. In a km race, A gives B a start of 20 seconds and still beat him by 40m. However, when he gives B a start of 25 sec they finish in a dead heat. What is A's speed in m/s?

• A's speed: 10 m/s
  A gives B a start of 20 seconds and beat him by 40m and
  when he gives B a start of 25 sec they finish in a dead heat..
  i.e. in 5 sec B completed 40m
  so B's speed = 40/5 = 8 m/s
  B's time over course = 1000/8 = 125 sec
  A gives B a start of 25 sec so A completed the race in 125-25 = 100sec
  A's speed will be = 1000/100 = 10 m/s
• 11 years agoHelpfull: Yes(1) No(0)
• Given:
  A gives B a start of 20 seconds and still beat him by 40m i.e B's speed=2m/s
  1 st condition: time taken by A + 20 sec=time taken by B
  => (1000/A)+20=(960/B)
  2 nd condition: time taken by A + 25 sec=time taken by B
  => (1000/A)+25=(1000/B)
  subtracting
  5=40/B
  => B=8m/s
  therefore A's speed = 10m/s.
• 11 years agoHelpfull: Yes(1) No(0)