Aptitude - Problems on Trains - Discussion

How the term 60 come? Please explain me.

s = 60km/hr
Time to cross pole = 9sec.
l = ?.

Time(train of length l) (pass a pole) = time(to cover l meters).

So,
9s = dist(l)/60km/hr
9s = dist(l)/1/6ms
9s = 6*dist
3/2 = dist
1.5 = dist
Hence option (d).

Given, S = 60 km/hr,
Time(T) = 9 sec and L(T)=?

Speed(S) = (60 * 5/18) = (50/3 m/sec).
L(T) = S * T.
L(T) = (50/3*9)m.
= 150m.

How we get 50, 3 and 18 in the solution?

Kilometers to meters: There are 1000 meters in 1 kilometer.

Hours to seconds: There are 60 minutes in 1 hour, and 60 seconds in 1 minute, so there are 60×60=3600 seconds in 1 hour.

So, to convert a speed from km/hr to m/sec, you multiply by 3600 seconds1000 meters​.

Now, let's simplify that fraction:
36001000 ​= 3610 ​= 185​.

150 is the answer.

First of all, we convert speed into m/sec because time is in sec, so we can divide.
Speed * 5/18
Then we can calculate using the length formula i.e.., speed * time.
50/3 * 9 = 150m
So, the answer is 150m.

Here we can use the formula;

The time taken by train to cross an object (i.e. man, pole, tree etc.)
T = L/S.

where T= time taken by train to cross an object.
L= Length of the train.
S= Speed of Train.

we have, S = 60 km/hr.
S = 60 * 5/18 ('*' symbol used for multiplication)
S = 16.66666 meter/second
T = 9 seconds.

Now, 9 = L/16.66666.
L = 9 * 16.
L = 149.99994~ 150 meter .
Answer = 150 meters.

@All.
speed(60)*1000(KM convert to meters)/3600(Hoursconvrt to sec)
->60*1000/3600 = 60 * 5/18 = 50/3.

@Anuradha.
= 50/3*9.
= 16.6666667*9,
= 150M answer.

Yes, the answer should be 150.