# A Train Speeds Past a Pole in 15 Seconds and a Platform 100 meter Long in 25 Seconds. Its Length is?

### Computer MCQs Series for PPSC, FPSC – Most Repeated MCQs | Set 6

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## Explanation

A train speeds past a pole in 15 seconds and platform in 25 seconds. Our final aim is to find out the length of the train. Train’s length would be calculated with speed distance time formula.

There are two things in this question.

• Trains crosses pole in 15 seconds; it means we are only talking about the length of the train.
• Trains crosses platform in 25 seconds; it means we are talking about length of the platform as well as the length of the train.

Let suppose the length of the train is y then

Total length = length of train + length of platform

Total length = y + 100

Another thing that we need is the speed of train which is very easy to find out.

Speed of train = y / 15

Now, we can calculate the length of the train by placing all the values in the speed distance time formula;

Speed = Distance / Time

Distance = Speed x Time

### To Find

Length of the train = ?

## Solution

As, we know that

Distance = speed x time

y + 100 = y/15 x 25

y + 100 = y/3 x 5

3(y + 100) = 5y

3y + 300 = 5y

5y – 3y = 300

2y = 300

### Conclusion

So if a train speeds past a pole in 15 seconds and a platform 100 meter long in 25 seconds. Its length is 150 m