Multiple choice

Passage

S.111-115) Directions for questions: 2 trains start from A and B and move towards B and A respectively. Train from A starts at 8 am and reaches B at 4 pm while train from B starts at 10 am and reaches A at 10 pm. Also, Train from A crosses a platform 200 m long in 10 seconds and a man moving in the same direction at 5 m/sec in 5 seconds.

Q.111) What is the length of train starting from A?

  1. a) 200 m

  2. b) 150 m

  3. c) 100 m

  4. d) 75 m
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Train A crosses a man moving in the same direction: (Length of train) / (Speed of train - Speed of man) = 5. L / (V - 5) = 5. Train A crosses a platform: (L + 200) / V = 10. L + 200 = 10V. From first, L = 5V - 25. Substitute into second: 5V - 25 + 200 = 10V. 5V = 175, V = 35. L = 5(35) - 25 = 175 - 25 = 150.

AI explanation

Using the relative speed formula for a train crossing a man walking in the same direction, the equation is L = (S - 5) * 5. Using the platform crossing data, the equation is L + 200 = S * 10. Expanding the first equation gives L = 5S - 25, and expanding the second gives L = 10S - 200. Setting them equal gives 5S - 25 = 10S - 200, which means the speed S is 35 m/sec. Substituting S back into L = 5S - 25 gives L = 5 * 35 - 25, making the length 150 meters.

Keep practicing — related questions