Multiple choice

Two 150 m long trains started at two different speeds. They were moving in opposite directions, are running at different speeds and cross each other in 6 seconds. One of the trains is moving at 1.5 times the speed of the other train. Find the speed of train which is running at higher speed.

  1. 98 km/h

  2. 108 km/h

  3. 125 km/h

  4. 135 km/h

  5. 145 km/h
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B Correct answer
Explanation

Relative speed = (150+150)/6 = 50 m/s = 180 km/h. Let speeds be v and 1.5v. v + 1.5v = 180 => 2.5v = 180 => v = 72. Higher speed = 1.5 * 72 = 108 km/h.

AI explanation

Let the slower train's speed be v m/s, so the faster train's speed is 1.5v m/s. Since they run in opposite directions, their relative speed is v + 1.5v = 2.5v m/s. The total distance covered to cross each other is 150 + 150 = 300 meters. Using the formula time = distance / speed, we write 6 = 300 / 2.5v, which simplifies to 2.5v = 50, giving v = 20 m/s. The faster train's speed is 1.5 multiplied by 20, which equals 30 m/s. Converting 30 m/s to km/h gives 30 multiplied by 3.6, which equals 108 km/h.

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