Rajdhani Express starts from Delhi at 12:00 pm and reaches Chandigarh at 2:30 pm and Doronto Express starts from Chandigarh at 12:15 and reach at Delhi at 2:15 . What will be the time when both the trains will cross each other?

A. 1:15 pm
B. 2:30 pm
C. 2: 15 pm
D. 3:30 pm

• Time taken by Rajdhani Express= 5/2 hrs.
  Time taken by Doronto Express= 2 hrs.
  Let distance between Delhi and Chandigarh = D
  Speed of Rajdhani= D/(5/2)= 2D/5
  Speed of Doronto= D/2
  Relative speed= 2D/5 + D/2 = 9D/10
  
  Now,
  at 12.15, Rajdhani express covers distance = 2D/5 * (15/60) = D/10
  Remaining distance = D- D/10 = 9D/10
  So at 12.15, both the trains are 9D/10 apart.
  Therefore time reqd = Distance/ Relative speed = (9D/10) / (9D/10) = 1 hr.
  
  Hence the two trains meet at (12.15 + 1 hr) = 1.15
• 9 years agoHelpfull: Yes(64) No(3)
• time taken by the first train=2+(30/60)=5/2 hrs.
  time taken by the 2nd train=2 hrs.
  Let distance between Delhi and Chandigarh=D
  speed of first train=5D/2.
  speed of 2nd train=D/2.
  time taken when both the trains will meet each other=D/(5D/2 +D/2)= 1hr and some few mins.
  
  So exact time when they will meet is 1:15 pm
• 9 years agoHelpfull: Yes(24) No(13)
• time taken by the 1st train=5/2 hrs
  time taken by the 2nd train=2hrs.
  speed=distnce/time.
  let the distance is D
  as in case of 1st train,speed=D/(5/2)=2D/5
  & speed of 2nd train is=D/2
  let the train will meet y hrs aftr 12.15.
  then Dy/2+2Dy/5=D;
  y(1/2+2/5)=1
  y=10/9hrs=>(10*60)/9=66min
  almost equals to 1hr 15min (ans)
• 9 years agoHelpfull: Yes(13) No(0)
• ans is 1:15 pm
  they meet each other
• 9 years agoHelpfull: Yes(12) No(7)
• This qstn can be solved by just seeing the options..its clear that 1:15 is the only possible answer,anyways thanx to others for the proper explanation :)
• 9 years agoHelpfull: Yes(6) No(1)
• first train starts at 12 o clock
  second train start at 12.15 o clock
  first train reach at 2.30 o clock
  second train reach at 20 o clock
  total time for first train to complete jorney is 2.30 hrs
  total time for second train to complete jorney is 2 hrs
  average time=2+2.30/2
  = 2.15
  the two trains are meet at 2.15 o clock
• 9 years agoHelpfull: Yes(5) No(39)
• option is a 1:15,
  because all other options are not satisfied
• 9 years agoHelpfull: Yes(2) No(0)
• juzzz check the options. it is option A
• 8 years agoHelpfull: Yes(2) No(0)
• Ans. -1.15
  sol.- let assume distance is 600km (becoz distance is same)
  1st train speed will be = 600/150 km/min
  2.30hr=150min
  600/150= 4km/min
  2nd train speed will be- 600/120 km/min
  2hr = 120 min.
  600/120=5km/min.
  1st train start 15 min before so its already cover distance of 60 km
  now 1st and 2nd train has same timing
  after 1hr 1st train will cover distance of 240+60.
  and 2nd also cover 300 in 1 hr
  so timing will be 1.15 .
• 9 years agoHelpfull: Yes(1) No(0)
• No need of applying formula for finding time we simply observe the options that are given 3 options are eleminated by common sense.Hence the remaining will be the answer....that is A.
• 6 years agoHelpfull: Yes(1) No(0)
• 1.15
  time taken by the first train=2+(30/60)=5/2 hrs.
  time taken by the 2nd train=2 hrs.
  Let distance between Delhi and Chandigarh=D
  speed of first train=5D/2.
  speed of 2nd train=D/2.
  time taken when both the trains will meet each other=D/(5D/2 +D/2)= 1hr and some few mins.
  
  So exact time when they will meet is 1:15 pm
  
• 9 years agoHelpfull: Yes(0) No(1)
• Nearly 1:15
  
• 9 years agoHelpfull: Yes(0) No(1)
• time taken by R(rajdhani)=2:30hr=5/2hr
  time taken by D(doronto)=2hr
  
  speed of R=2X/5
  Speed of D=X/2
  
  let the distance is X and they meet t hrs after 12:15
  then
  distance coverd by R in (t+1/4)hrs+distance covered by D in t hrs = X
  
  2X/5(t+1/4) + X/2(t) = X
  2/5(t+1/4)+ t/2 = 1
  hence t = 1 hrs
  and they meet after 12:15+ 1hr =1:15 pm (ans)
  
  
• 9 years agoHelpfull: Yes(0) No(0)
• 1.15
  time taken by the first train=2+(30/60)=5/2 hrs.
  time taken by the 2nd train=2 hrs.
  Let distance between Delhi and Chandigarh=D
  speed of first train=5D/2.
  speed of 2nd train=D/2.
  time taken when both the trains will meet each other=D/(5D/2 +D/2)= 1hr and some few mins.
  
  So exact time when they will meet is 1:15 pm
  
• 9 years agoHelpfull: Yes(0) No(1)
• let the dist. between delhi nd chandigrh be 10 km, therefore speed of rajdhani=10/2.5=4km/hr and speed of duranto =10/2= 5km/hr.
  distance travelled by rajdhani from 12pm to 12;15 pm is 1 km
  remainin distance =9 km that is coverd by two trains in 9/(4+5)=1hr {relative velocity}
  hence time of meeting is 1:15 pm
• 7 years agoHelpfull: Yes(0) No(0)
• Suppose total distance between two cities is x.
  Rajdhani express takes 30 minutes more than Doronto express;
  let the Time be T when they will meet.
  Speed of rajdhani =x/(5/2);
  speed of doronto express =x/2;
  so by equating the distance x to the total distance travelled by both train.
  Beacause Rajdhani express has taken 30 minutes more as it can be seen in the equation.
  X=x*(t+1/2)/(5/2) + x*t/2;
  we will get t=1
  so both will meet after 1 hour (12:15+1=1:15);
• 6 years agoHelpfull: Yes(0) No(0)