Multiple choice general knowledge math & puzzles

In a circular track of 100 kms run A and B.A's speed is 25km/hr and B's is 15km/hr.In hw much time will they cross each other for the 3rd time?

  1. 25 hrs

  2. 20 hrs

  3. 25.71 hrs(approx)

  4. 40 hrs
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A gains 10 km/hr on B (25-15=10). In 20 hours, A gains 200 km, which is 2 full laps of the 100 km track. Starting from opposite points, they meet after 10 hours (A overtakes B), then at 20 hours (A's 2nd lap advantage means 3rd crossing). The key insight: relative gain of 100 km = 1 lap = 1 crossing. So 200 km gain = 2 laps = 3rd crossing.

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