If A driver drives a car four times a lap 10,20 30,60 kmph what is his average speed.

• For simplicity, assume the distance of the lap is 60km
  When the speed is
  10kmph, time taken to complete the lap=6hrs.
  20kmph, time taken to complete the lao=3hrs
  30kmph, time taken to complete the lap=2hrs
  60kmph, time taken to complete the lap=1hr.
  Average speed=total distance/time taken=240/12=20kmph
• 12 years agoHelpfull: Yes(36) No(6)
• Let the lap be x km
  Time taken by him to cover 4x km
  =x/10 +x/20 +x/30 +x/60 hrs
  =12x/60 hrs
  =x/5 hrs
  Therefore average speed
  =4x divided by x/5
  =4x*5/x
  =20 kmph
• 11 years agoHelpfull: Yes(33) No(1)