240 meters long train crosses a pole in x seconds, while the train can cross a…
2023
240 meters long train crosses a pole in x seconds, while the train can cross a 360 meters long platform in x+9 seconds. Find the time taken by the train to cross a dog who is running in the direction of the train at speed of 36 km/hr.
- A.
x seconds
- B.
2x seconds
- C.
x+2 seconds
- D.
x−1 seconds
- E.
x+3 seconds
Attempted by 4 students.
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Correct answer: C
The train speed from crossing a pole is 240/x m/s. Crossing a 360 m platform gives 600/(x+9) = 240/x, so x = 6 and train speed = 40 m/s. The dog runs at 36 km/h = 10 m/s in the same direction, so relative speed = 30 m/s and time = 240/30 = 8 seconds = x + 2.