A person travels at a speed of 10 mph from one city to another. However while returning as there was not much traffic. He came with a speed of 15mph. what is his average speed?

• Average speed = 2xy/(x+y) = (2*15*10)/25 = 12mph
• 14 years agoHelpfull: Yes(4) No(0)
• Ans:12mph
  
  Speed = Distance/time
  Let x be distance
  then time taken to travel (going) =x/10
  time taken (return) =x/15
  Average speed = total distance/total time taken
  =2x/(x/10+x/15)
  on solving this we get average speed =12mph
• 14 years agoHelpfull: Yes(2) No(0)
• 12 mph
• 14 years agoHelpfull: Yes(1) No(1)
• 12.5 mph
• 14 years agoHelpfull: Yes(1) No(3)
• 12mph
  avg speed=total dist/tot time
  let x be distance bw cities
  so avg speed=2x/((x/10)+(x/15))
  =12 mph
• 14 years agoHelpfull: Yes(0) No(0)
• 12mph
• 14 years agoHelpfull: Yes(0) No(0)
• let distance be x
  t1=x/15 t2=x/10
  total t taken=t1+t2=x/6
  so av speed=2x/x/6=12
• 14 years agoHelpfull: Yes(0) No(0)
• when he is going the speed is 10mph,
  while returning the speed is 15mph
  the average speed is : (going speed + returning speed) / 2
  so (10 mph + 15 mph) / 2 = 12.5 mph
• 7 years agoHelpfull: Yes(0) No(0)