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Bunuel
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Two trains traveling at same speed take 10 seconds and 15 seconds resp 03 Jan 2020, 02:17
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C
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Question Stats:

52% (01:53) correct 48% (01:30) wrong based on 193 sessions

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Two trains traveling at same speed take 10 seconds and 15 seconds respectively to cross a telegraph post. Find the time taken by the trains to cross each other if traveling in opposite directions.

A. 6 sec
B. 12 sec
C. 12.5 sec
D. 25 sec
E. Cannot be determined
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C
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Two trains traveling at same speed take 10 seconds and 15 seconds resp Updated on: 14 Jun 2024, 09:44
Originally posted by CareerGeek on 04 Jan 2020, 21:00.
Last edited by CareerGeek on 14 Jun 2024, 09:44, edited 1 time in total.
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Bunuel
Two trains traveling at same speed take 10 seconds and 15 seconds respectively to cross a telegraph post. Find the time taken by the trains to cross each other if traveling in opposite directions.

A. 6 sec
B. 12 sec
C. 12.5 sec
D. 25 sec
E. Cannot be determined
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Let the speed of each train = v
—> Length of first train = v*10 = 10v and
Length of second train = v*15 = 15v

When they crossed each in opposite direction, each train has to cross 10v + 15v = 25v to completely go past each other

—> Time taken to cross each other = 25v/(v + v) = 25v/2v = 12.5

IMO C

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Two trains traveling at same speed take 10 seconds and 15 seconds resp 04 Jan 2020, 22:57
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Bunuel wrote:
Two trains traveling at same speed take 10 seconds and 15 seconds respectively to cross a telegraph post. Find the time taken by the trains to cross each other if traveling in opposite directions.

A. 6 sec
B. 12 sec
C. 12.5 sec
D. 25 sec
E. Cannot be determined

As two trains traveling at same speed, Let speeds for two trains = x
Distance for first train = 10x
Distance for second train = 15 x

Time needed for two trains to cross each other = 25/2x
= 12.50(C)
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Two trains traveling at same speed take 10 seconds and 15 seconds resp 05 Jan 2020, 12:29
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Solution



Given
In this question, we are given that
    • Two trains traveling at same speed take 10 seconds and 15 seconds respectively to cross a telegraph post

To find
We need to determine
    • The time taken by the trains to cross each other, if the trains are traveling in opposite directions

Approach and Working out
Let us assume that the equal speed of both the trains is v, and the individual lengths of the trains are L1 and L2 respectively.
While crossing a telegraph post, the trains are effectively crossing their own lengths.
Hence, we can write:
    • L1 = 10v
    • And L2 = 15v

When travelling from the opposite direction, they will travel a distance equal to the combined lengths of the trains
So, total distance travelled = L1 + L2 = 10v + 15v = 25v

As travelling from the opposite direction, the relative speed of the trains = v + v = 2v
    • Hence, the time taken = 25v/2v = 12.5 seconds

Thus, option C is the correct answer.

Correct Answer: Option C
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Two trains traveling at same speed take 10 seconds and 15 seconds resp 05 Jan 2020, 12:49
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Its 12.5 sec.

Sol: Both have same speed,so let speed be = s

Length of T1 = 10xs
Length of T2 = 15xs

Now calculate the time to cross each other by relative formula of speed: and since they are going in opposite directions then: (10s+15s)/2s= 12.5sec

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Two trains traveling at same speed take 10 seconds and 15 seconds resp 31 Aug 2023, 22:30
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Given: Two trains traveling at same speed take 10 seconds and 15 seconds respectively to cross a telegraph post.

Asked: Find the time taken by the trains to cross each other if traveling in opposite directions.

Let the length of trains be x & y meters respectively and speed of trains be v m/s.

In crossing a telegraph post.
Speed = v
x = 10v
y = 15v

In crossing each other
Distance = x+ y
Speed = 2v
x + y = 10v + 15v = 25v = 12.5 * 2v
Time taken by the trains to cross each other = 12.5 sec

IMO C
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Two trains traveling at same speed take 10 seconds and 15 seconds resp 31 Oct 2025, 13:37
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