Question:medium

Trains A and B start traveling at the same time towards each other with constant speeds from stations X and Y, respectively. Train A reaches station Y in 10 minutes while train B takes 9 minutes to reach station X after meeting train A. Then the total time taken, in minutes, by train B to travel from station Y to station X is

Updated On: Jan 15, 2026
  • 15

  • 12

  • 6

  • 10

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The Correct Option is A

Solution and Explanation

1. Given:

  • Train A arrives at station Y 10 minutes after meeting Train B.
  • Train B arrives at station X 9 minutes after meeting Train A.
  • Let the meeting point be M.

2. Let t represent the time (in minutes) each train spent traveling to point M.

Based on the provided information:

  • Train A: Traverses from X to M in \( t \) minutes, then from M to Y in \( 10 - t \) minutes.
  • Train B: Traverses from Y to M in \( t \) minutes, then from M to X in 9 minutes.

Since the distances XM and MY are equal for both trains (as they meet at the same point), the ratio of their travel times is inversely proportional to their speeds:

\[ \frac{t}{9} = \frac{10 - t}{t} \]

3. Equation Solution

Upon cross-multiplication:

\[ t^2 = 9(10 - t) \] \[ t^2 = 90 - 9t \Rightarrow t^2 + 9t - 90 = 0 \]

Solving the quadratic equation:

\[ (t + 15)(t - 6) = 0 \Rightarrow t = -15 \text{ or } t = 6 \]

As time cannot be negative, the valid solution is:

\[ t = 6 \]

4. Conclusion

Train B's travel time:

\[ \text{From Y to M: } t = 6 \text{ minutes} \] \[ \text{From M to X: } 9 \text{ minutes} \] \[ \Rightarrow \text{Total travel time from Y to X = } 6 + 9 = \boxed{15} \text{ minutes} \]

Final Answer: 15 minutes

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