Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 26)
26.
Two trains are running at 40 km/hr and 20 km/hr respectively in the same direction. Fast train completely passes a man sitting in the slower train in 5 seconds. What is the length of the fast train?
Answer: Option
Explanation:
Relative speed = (40 - 20) km/hr = | ![]() |
20 x | 5 | ![]() |
m/sec = | ![]() |
50 | ![]() |
m/sec. |
18 | 9 |
![]() |
![]() |
50 | x 5 | ![]() |
m = | 250 | m = 27 | 7 | m. |
9 | 9 | 9 |
Discussion:
72 comments Page 7 of 8.
Rohit Parmar said:
6 years ago
How to simplify 250/9 to 27*7/9?
Please explain clearly.
Please explain clearly.
Shital said:
6 years ago
Please, explain this how 250/9 to 27 * 7/9?
(3)
Shri said:
6 years ago
@Shital.
It is a mixed fraction method, 27 * 9 = 243.
243 + 7 = 250.
It is a mixed fraction method, 27 * 9 = 243.
243 + 7 = 250.
Ananth said:
6 years ago
Divide 250 by 9. The Remainder * Quotient/Divisor rule then follows.
G Rajesh said:
6 years ago
I think if they asked to find the length of the smaller train we have to use same formula as explained above in explaination box. We can assume that length of two trains are same.
A Dwivedi said:
6 years ago
This question definitely depends upon where the person is sitting in the second train - middle, end or int engine of the train depending on which the total time taken by the fast train to pass him completely will change. And the solution given is correct only if the person is sitting at the end of the slower train. Can someone explain this, please?
(2)
YOGANANDA NAIDU said:
5 years ago
@Dwivedi.
Here what they asked is, the length of the faster train.
If you want the length generally we multiply speed and time.
In this question, you think that you are in a slower train it's speed is 20kmph in which ever the place either in front middle or in last your speed is 20kmph. The faster train has to cross you so the speed of train relative to you is 20kmph or 50/9mps.
Length of the faster train = relative speed in mps*time in sec = 50/9 * 5 = 250/9 = 27 * 7/9.
.
Here what they asked is, the length of the faster train.
If you want the length generally we multiply speed and time.
In this question, you think that you are in a slower train it's speed is 20kmph in which ever the place either in front middle or in last your speed is 20kmph. The faster train has to cross you so the speed of train relative to you is 20kmph or 50/9mps.
Length of the faster train = relative speed in mps*time in sec = 50/9 * 5 = 250/9 = 27 * 7/9.
.
(2)
Sagar said:
4 years ago
Why we don't count two train lengths? Anyone explain me.
(6)
Siddarth said:
3 years ago
250 /9 = 27.777777778 means then how to convert it into 27*7/9?
Please explain in detail.
Please explain in detail.
(1)
Shreya said:
3 years ago
@Siddarth.
You don't need to divide 250/9 completely because we don't need the answer in decimals according to the options.
You should divide 250 by 9 until you cannot divide it further without the need of a decimal i.e. when the quotient is 27 and the remainder is 7.
And then you can write it in the form of a mixed fraction i.e. quotient remainder/divisor or 27 7/9 as given in option C.
You don't need to divide 250/9 completely because we don't need the answer in decimals according to the options.
You should divide 250 by 9 until you cannot divide it further without the need of a decimal i.e. when the quotient is 27 and the remainder is 7.
And then you can write it in the form of a mixed fraction i.e. quotient remainder/divisor or 27 7/9 as given in option C.
(5)
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