Multiple choice

If two trains are moving towards each other with velocities of 50 km/h and 60 km/h respectively. A fly flies to and fro in between them at a speed of 5 km/h. The initial distance between the trains is 220 km. How much distance will the fly cover before the trains crash?

  1. 5 km

  2. 10 km

  3. 15 km

  4. 20 km
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The trains are 220 km apart and closing at 50+60 = 110 km/h. Time until crash = 220 / 110 = 2 hours. The fly travels at 5 km/h for 2 hours, so distance = 5 * 2 = 10 km.

AI explanation

The relative speed of the two trains moving towards each other is 50 km/h plus 60 km/h, which equals 110 km/h. The time it takes for the trains to crash is the initial distance of 220 km divided by the relative speed of 110 km/h, yielding 2 hours. The fly travels at a constant speed of 5 km/h for these 2 hours, so the total distance covered by the fly is 5 multiplied by 2, which equals 10 km.

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