Aptitude - Problems on Trains - Discussion

hai!frinds,.
in this above problem they given speed of the one object.
we know that if the two objectives are move in the same direction then the formula is"(A-B)"(assume A is one objective and B is another objective).so,nw we know one objective speed(taken as B speed we know),that is subtutited in above.

then s=(A-5).(here it is the speed of the train)
1.in the problem train(objective) speed is given in the form of seconds,so convert the seconds into the km/hr.because of the one objective speed is give in the form of km/hr and also answer is given in the form of km/hr.
2.while the conversion we have to follow the following,
i)if we covert m/sec inti km/hr then multiplis with"8/15"
ii)if we convert km/hr into the m/sec then multiplies with "15/8"
3.we know the formula for speed is
"speed=Distance/Time"(s=D/T)
s=125/10 m/sec [here 125 is the distance,and 10 is the speed of the objective]
the conversion
s=125/10*(18/5)km/hr
=45.
4.in starting we initialse the speed(s)=A-5
then subtuted that speed in the above,
A-5=45
A=50.
therefore the speed of the train(another objective) is "A=50".

Hi friends,the problem is very simple.Think in this way.Assume that the man is not moving(standing like a pole),now findout the speed of the train using the data.
LENGTH OF THE TRAIN=125m.
TIME TAKEN BY THE TRAIN TO CROSS THE MAN(assume standing)=10sec
w k t velocity=distance(length of the train)/time.
v=(125/10)m/s
v=(25/2)m/s
convert m/s into km/hr
v=(25/2)* (3600/1000) or (25/2)*(18/5)
v=45 km/hr
45 km/hr is the train speed if the person is standig(not moving).
But in the problem person is moving and that to he is moving in the same direction in which train going,so that's y add the speed of the man to the speed of the train then we will got the correct answer.
speed of the train+speed of the man=45+5=50 km/hr.

NICE EXPLANATION ABHISHEK.

Ramesh chandran.

CLEAR explanaTION. THANKS.

Hi Tahira,

You just cancel 125/10 using multiples of 5.

125/10=25/2=12.5.

Hai fnds.

Howz the 12.5 is converted into 25.

Please explain.

hai raghu, in the question man's speed is given in km/hr so we gonna convert train's speed to km/hr which is actually in m/s
1 m/s = 3600 km/1000 hr
125/10 m/s= (125/10)*(3600/1000)

How it is 3600/1000. It will come as 1000/3600 only. Please explain.

@kumar
cause speed=distance/time

Why 125 is divided by 10?