Multiple choice

Subham gets on the lift at the 11th floor of a building and rides up at speed of 57 floors per minute. At the same time, Sonali gets on a lift at the 51st floor of the same building and rides down at the rate of 63 floors per minute. If they continue travelling at these rates, then at which floor will their paths cross?

  1. 45

  2. 36

  3. 52

  4. 30
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

They start 40 floors apart (51-11) and close the gap at combined speed 120 floors/min. Time to meet is 40/120 = 1/3 min. Subham travels 57×1/3 = 19 floors up from floor 11, reaching floor 30. Option A (45) is above both starting positions. Option B (36) and C (52) ignore the relative motion.

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