Q. There ia truck which should reach some place at 11'o clock , if it travels with 30 mph it reaches i hour before, if it travles with 20 mph it reaches 1 hour late. what is the distance it must be travlled and what is the speed it must maintain to rech at exact time?

• let S T D are the speed time and distance
  S=D/T
  according to question,
  30=D/(T-1)..........1
  and
  20=D/(T+1)..........2
  dividing equation 1 by 2 we get T=5 hours
  now,
  for distance put value of T in equ 1
  then D=120 m
  
  now,
  for exact time s=d/t
  =120/5
  =24 mph ans..
• 11 years agoHelpfull: Yes(72) No(1)
• just do the simple calculation
  find the average speed
  i.e.
  2*30*20/20+30
  =24mph
  now find the no.which is divisible by 20.30 &24
  and that no.is 120..................
  very easy with approach
  
• 11 years agoHelpfull: Yes(12) No(1)
• let the distance be x m(meter)
  s1=30mph
  s2=20mph
  t1=x/30h
  t2=x/20h
  time difference=2h(1h before+1h late)
  now,
  t2-t1=2h
  (x/20)-(x/30)=2
  on solving x=120m
  distance=120 m
  for time
  distance/speed =time
  so
  let Yh is the exact time
  (120/30)=Y-1
  on solving y=5h
  so,120/5=24mph is the exact speed to reach in exact time
• 11 years agoHelpfull: Yes(3) No(0)
• let T is exact time has to be taken by truck
  let X is distance travelled
  so
  X=30(T-1)
  X=20(T+1)
  30(T-1)=20(T+1)
  
  T=5
  
  X=30(5-1)
  X=120miles
  
  speed=X/T;
  =120/5
  =24mph
• 11 years agoHelpfull: Yes(3) No(0)
• The Answer Should be 120m in 5hrs with the speed of 24m/h
  Let t be the xact time the truck takes to cover the distance with speed Smph.
  Let D1 be the distance travelled with 30mph in t-1 hr
  hence we have D1=S1*t1=30*(t-1)
  Let D2 be the distance travelled with speed 20mph in t+1 hr
  hence D2=S2*t2=20*(t+1)
  Since it sovers the same distance in both the cases ie the total distance
  D1=D2=D
  Solving D1=D2
  We get t=5hr therby D1=D2=120m
  and hence S=D/t=120/5=24mph
• 11 years agoHelpfull: Yes(1) No(0)
• hey plz send me the infosys papers @.. emmarockstar1@gmail.com
• 11 years agoHelpfull: Yes(0) No(1)
• speed 24kmph, distance 120km
• 11 years agoHelpfull: Yes(0) No(0)
• distance is 120 and speed is 24 mph
• 11 years agoHelpfull: Yes(0) No(0)