Aptitude - Problems on Trains - Discussion

How did the 5/18 came? Can anyone explain it?

First convert the unit km/hr into m/s, because the length of the train is given in meters.

->so ,1km=1000m and 1 hr=1*60*60=3600 secs.

Now ,as we all know, the formula for speed in terms of distance is
speed =distance /time.
=>(60*1000/3600) m/s = distance/9 secs.
=>60*5/18 = length of train/9(time taken to cross the pole by train)
=>9*60*5/18 = length of the train.
=>length of the train =150 m.

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.

(MLT) Medical Lab Technician.

1 km = 1000 m,
1 hr has 3600 sec.
So, 1 km/hr = 1000m/3600s = 5/18 m/s.

The speed of train in 1sec =(60*5)/18=16.66666666666667 m/sec,
As we know that an object or a thing can be crossed with the length of a train
we took 9sec then
The length of train = 16.66666666666667 * 9 = 150 m.

= 60×5/18.
= 300/18 (50×6=300 ,3×6=18).
= 50/3,
= 50/3×9,
= 50×3,
= 150.

60 *5/18 = 50/3.
450m/3 = 150m.

Speed = 60 km/hr= 60* (5/18) m/s = 16.67 m/s.
Time= 9 sec.
Distance = speed* time.
Distance = 16.67 * 9 =150m.

Length = time/speed.
= 9sec/60kmhr.
= 0.15km = 150meter.