1/3 of a certain journey is covered at the rate of 25km/hr,1/4 at the rate
of 30 km/hr and the rest is 50 km/hr.the avg speed for the whole journey is :
option: 30,30,33 1/3,37 1/12 km/hr

• Let total distance be x.
  T=x/3*25+x/4*30+5x/12*50=x/75+x/120+x/120.
  Therefore avg.speed=x/9x/300=100/3
• 8 years agoHelpfull: Yes(9) No(4)
• let assume total distance will be 120km then
  distance traveled at teh speed 25km/hr=1/3*120=40km the time=40/25=1.6hrs
  distance traveled at the speed 30km/hr=1/4*120=30kmthe time is=30/30=1 hr
  then remaining distance is 120-40-30=50km
  the time taken to travel 50km=50/50=1hr
  so total time is=1.6+1+1=3.6 hrs
  so avg speed =120/3.6=33.33km/hr
• 9 years agoHelpfull: Yes(4) No(2)
• ans-> 33.33kmph
  
  avg speed= total dist / total time
  
  total distance= d(say)
  
  total time= d/(3*25) + d/(4*30) + 5d/(12*50)
  
  putting the values in above formula
  we get avg speed as 33.33kmph
• 8 years agoHelpfull: Yes(1) No(1)