On a journey across HYD, a taxi averages 30kmph for 60% of distance and 20kmph for 20% of diatance,and 10kmph for remainding.what is the average speed of whole journey?

• let the total distance be 100km
  so, journey was 60 km at 30kmph speed & 20 km at 20kmph& 20 km at 10kmph
  time taken for first 60km distance= dist/speed = (60/30)= 2hr
  similarly for 20km, time=1hr
  for rest of the jrny= time=2hr
  avg speed=(total distance/total time)
  =(100)/(1+2+1)
  =20km
• 11 years agoHelpfull: Yes(2) No(0)
• ans:- 20
  Let distance = x
  Time taken for whole journey is
  
  (60%x/30)+(20%x/20)+(20%x/10)
  if solve we get x/20
  
  so total time = x/20
  
  avg. speed= total distance/total time
  
  = x/(x/20)
  avg. speed =20
  
• 11 years agoHelpfull: Yes(0) No(1)
• ans : 20 kmph
  
  explanation:
  let total distance be x km.
  taxi covers 60% of distance in avg speed of 30kmph
  so time taken to cover 60% of the distance i.e 0.6x km=0.6x/30 hr=x/50 hr.
  similarly we get ,
  time taken to cover 20% in 20 kmph=0.2x/20=x/100 hr
  time taken to cover remaining distance i.e 20% in 10 kmph =0.2x/10=x/50 hr
  
  total time taken by the taxi to cover all the distance=x/50+x/100+x/50 hr= x/20 hr
  average speed of whole journey= total distance/total time=x/(x/20) = 20 kmph
  
  QED...:)
• 11 years agoHelpfull: Yes(0) No(0)