Aptitude - Problems on Trains - Discussion

Good explanation, Thanks all.

Good explanation. Thanks all.

Good understanding and thinking questions.

Agree, 150 is the correct answer.

What is a pole?
In this problem, a “pole” is just a single post or point beside the railway track.
Distance covered by the train while crossing the pole = length of the train.

Formula:
Speed = Distance/Time.
And Distance = Speed × Time.

Convert km/hr into meters per second (m/s):
NOTE: 1 km/hr = 1×(5/18) m/s
60 km/hr = 60×(5/18) = 300/18 m/s
Multiply by time to get distance (length of the train): Distance = (300/18)×9 = 150 meters,
Answer: The length of the train = 150 meters.

A km/hr = [a×5÷18]m/s.
60 = [9×5÷18].
5÷2×60 = 150 meter.

Pole means? Please explain me.

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.

How come 5/18? Please explain.

We are given speed as 60 km/h.
But we need the answer in meters per second (m/s).

1. First, we convert kilometres to metres:
1 km = 1000 meters.
So 60 km = 60 × 1000 = 60,000 meters.

2. Next, convert hours to seconds:
1 hour = 60 minutes
= 60 × 60 = 3600 seconds.

3. Now divide the distance by time:
60,000 ÷ 3600 = 16.666… ≈ 16.67 m/s.
then 16.6 x 9 = 150.

Then the final answer is 150 meters.