Official Quant thread for CAT 2013

MBA CAT 2024
10861
@nole said:
@ScareCrow28 How do we know kalu will take 10s to cover 30 mtrs? can u please explain the line "sambhu beats kalu by 30 metres or 10 seconds" . I am not able to create a equation out of that line.
See, sambhu beats kalu by 30 mtrs and 10 sec means that sambhu is faster and kalu is behind sambhu and he will take 10 secs to cover those 30 mtrs to come at his place
10862
@ScareCrow28 Thanks 😃 in question it is given 30 metres OR 10 seconds.U have written 30 mtrs and 10 seconds.u meant OR only right ? or it does it make a difference if it is 'OR' or 'AND' ?
10863
@nole said:
@ScareCrow28 Thanks in question it is given 30 metres OR 10 seconds.U have written 30 mtrs and 10 seconds.u meant OR only right ? or it does it make a difference if it is 'OR' or 'AND' ?
OR :) It can't be and because these are data of two different races. In first the time for which they ran is same whereas in second race the distance for which they ran is same.
10864
A & B both start running around circular track in the same direction. A is on bicycle & B is on foot. A catches up B, as A's speed > B's. The moment he meets B, he turns around & head back towards the startng point. When A reaches starting point he again meets B who has just finished his 1st round. Ratio of speed of A & B ??
10865
@hiteshkhurana82 said:
A & B both start running around circular track in the same direction. A is on bicycle & B is on foot. A catches up B, as A's speed > B's. The moment he meets B, he turns around & head back towards the startng point. When A reaches starting point he again meets B who has just finished his 1st round. Ratio of speed of A & B ??
(root2)+1:1
10866
@19rsb said:
(root2)+1:1
sar btaa bhi do kaise??
10867
@hiteshkhurana82 said:
sar btaa bhi do kaise??
let perimeter of circle be y and distance of point (from starting point) at which both meet for the 1st time be x then
ratio of speeds=(y+x)/x=x/(y-x)
solve to get y=(root2)x
then,speed ratio = {(rt2)x+x}/x=(rt2)+1
10868
@hiteshkhurana82 said:
A & B both start running around circular track in the same direction. A is on bicycle & B is on foot. A catches up B, as A's speed > B's. The moment he meets B, he turns around & head back towards the startng point. When A reaches starting point he again meets B who has just finished his 1st round. Ratio of speed of A & B ??
1+ root2:1
10869
3 persons A,B,C start runnin simultaneously on 3 concentric circular tracks from 3 collinear points P,Q,R respectively which r collinear wid de centre and r on de same side of de centre. de speed of A,B,C r 5m/s,9m/s,8m/s respectively. de lengths of de tracks on which A, B, C r running r 400m,600m,800m respectively.

1) If A and B run in de clockwise direction and C in de anti clockwise direction, after how much time €™llde positions of A,B,C be collinear wid de centre and on de same side of de centre, for de first time after dey start?
a)200 sec
b)400 sec
c)600 sec
d)800 sec

2) If A runs in de clockwise direction and C in de anti clockwise direction, after hw much time €˜ll de positions of A and C be collinear wid de centre (and on de same side), for forth time after dey start?
a)1600/9 sec
b)160 sec
c)1600/11 sec
d)200 sec
10870
vinay fires two bullets from the same place at an interval of 12 minutes but raju sitting in a train approaching the place hears the second report 11 minutes 30 seconds after the first.What is the approximate speed of the train ?(is sound travels at the speed of 330 metres per second)

ďťż
10871
@hiteshkhurana82 said:
3 persons A,B,C start runnin simultaneously on 3 concentric circular tracks from 3 collinear points P,Q,R respectively which r collinear wid de centre and r on de same side of de centre. de speed of A,B,C r 5m/s,9m/s,8m/s respectively. de lengths of de tracks on which A, B, C r running r 400m,600m,800m respectively.1) If A and B run in de clockwise direction and C in de anti clockwise direction, after how much time €™llde positions of A,B,C be collinear wid de centre and on de same side of de centre, for de first time after dey start?a)200 secb)400 secc)600 secd)800 sec2) If A runs in de clockwise direction and C in de anti clockwise direction, after hw much time €˜ll de positions of A and C be collinear wid de centre (and on de same side), for forth time after dey start?a)1600/9 secb)160 secc)1600/11 secd)200 sec
1) 400s

2) 1600/9

its clear that A will take 40 seconds to complete half cycle and C will take 50

so they are collinear for the first time somewhere between 40 and 50 s

going by the options only 400/9 seconds satisfies

10872
@nole said:
vinay fires two bullets from the same place at an interval of 12 minutes but raju sitting in a train approaching the place hears the second report 11 minutes 30 seconds after the first.What is the approximate speed of the train ?(is sound travels at the speed of 330 metres per second)
330*30/12*60 = 55/4 = 13.5 m/s ?
10873
@nole said:
vinay fires two bullets from the same place at an interval of 12 minutes but raju sitting in a train approaching the place hears the second report 11 minutes 30 seconds after the first.What is the approximate speed of the train ?(is sound travels at the speed of 330 metres per second)
For this, I will take the sound as a "car" approaching at a speed of 330m/s

So, the two cars left at an interval of 12 minutes as seen by a person on ground, and the person in train meets them at an interval of 11 minutes 30 seconds

Let the person in train meet the first car at time 't', so the equation will be

330*t - 330*(t - 12) = (330 + v)*(11.5) => v = 330/23 m/s = 14.35 m/s ?
10874

plz help me

10875
@YouMadFellow said:
For this, I will take the sound as a "car" approaching at a speed of 330m/s So, the two cars left at an interval of 12 minutes as seen by a person on ground, and the person in train meets them at an interval of 11 minutes 30 secondsLet the person in train meet the first car at time 't', so the equation will be330*t - 330*(t - 12) = (330 + v)*(11.5) => v = 330/23 m/s = 14.35 m/s ?
Units ka golmaal hai.. 330m/s and 12 minutes = 12*60 sec
10876
@YouMadFellow
@ScareCrow28 answer is 330/23 m/s
10877
@nole said:
vinay fires two bullets from the same place at an interval of 12 minutes but raju sitting in a train approaching the place hears the second report 11 minutes 30 seconds after the first.What is the approximate speed of the train ?(is sound travels at the speed of 330 metres per second)
330*30 / 690 ?
10878
@ScareCrow28 said:
Units ka golmaal hai.. 330m/s and 12 minutes = 12*60 sec
Doesn't matter, as long as both the LHS and RHS maintain the same units 😃
10879
@nole said:
vinay fires two bullets from the same place at an interval of 12 minutes but raju sitting in a train approaching the place hears the second report 11 minutes 30 seconds after the first.What is the approximate speed of the train ?(is sound travels at the speed of 330 metres per second)
say s mps

12*60*330 = (s+330)*690

==> s=330/23
10880
@nole said:
vinay fires two bullets from the same place at an interval of 12 minutes but raju sitting in a train approaching the place hears the second report 11 minutes 30 seconds after the first.What is the approximate speed of the train ?(is sound travels at the speed of 330 metres per second)
speed of the bullet/speed of train=time utilized/time saved
330/x=690/30
x=14.3 m/s