Aptitude - Problems on Trains - Discussion

How did 5/18 came here? please explain.

but how do we convert km into m?? and where does that 5/18 come from?

Anyone, please explain to me.

How 5/18 came? Anyone, please explain to me.

from the above statement:

60,000 m is crossed in=>3600 s.
? m is crossed in=> 9 s.

60000/x => 3600/9.

Do a normal cross-division method to find x. That's the answer.

60 * (5/18) = 50/3.
Speed = Distance/ Time.
Distance = Speed * Time = (50/3) * 9,
= 150 m.

The speed of the train = 60km/hr.
Pole cross time = 9 sec
So, convert speed into secs 1hr =60 minutes per minute 60 sec.
to convert 1hr in sec = 60 * 60 = 3600sec.
Now, convert km into meters 1km = 1000m.
then, speed = (60 * 1000/3600) m/s.
= (60 * 5/18) = 16.67m/s.
Now, the length of the train = speed * time.
= 16.67 * 9 = 150m.

How 5/18 came I will explain.

1 km = 1000 m.
1hr = 60min.
1 min = 60sec.
60min = 3600 sec.
1000/3600 = 5/18.
(Cancelling two zeroes up and down and 2*5 = 10 and 2*18=36).

Why we are calculating 5/18 not 18/5? Please explain it.

To know: If the train crosses the pole.
The total distance travelled by train would be its length.
To do: So, calculate the distance travelled by the train to cross the pole.
Formula: Distance(d) = Speed x Time.
Given: Speed of Train 60 km/hr, Time taken to cross a pole = 9 seconds.

Steps:
1. the speed is given in "km/hr" but time is in "Seconds"... Multiplying speed in km/hr directly with time in seconds is not valid.
2. Now, to convert to m/s...
speed = 60 x 5/18 = 16.67 m/s.
3. Distance(d) = 16.67 x 9 = 150 meters.

Final answer: The length of the train is 150 meters.

Convert km to m - 60000.
Convert hr to sec - 3600.

Sso, 60000/3600 = 16.666(speed) * 9 (time) = 150.