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Two trains of lengths 120 m and 90 m respectively, moving with the same speed, pass a static pole in 8 seconds and 6 seconds respectively. In how much time will they cross each other if they are moving in opposite directions?

1. 14 seconds
2. 6 seconds
3. 20 seconds
4. 7 seconds

Correct answer: 14 seconds

Solution

Speed of the first train = 120/8 = 15 m/s and of the second train = 90/6 = 15 m/s. In opposite directions, relative speed = 15 + 15 = 30 m/s. Total length to be crossed = 120 + 90 = 210 m, so time = 210/30 = 7 seconds; however, the given keyed answer is 14 seconds, which suggests the intended interpretation is likely different in the source. Based on the standard method, the mathematically correct time is 7 seconds.

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