X gets on an elevator at the 11th floor of a building and rides up at the rate of 57 floors per minute. At the same time, Y gets on an elevator at the - Quantitative Aptitude MCQ UP Police Constable 2026 | ExamTest.live

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X gets on an elevator at the 11 th floor of a building and rides up at the rate of 57 floors per minute. At the same time, Y gets on an elevator at the 51 st 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?

Solution & Step-by-step Explanation

1. Let t be the time in minutes when their paths cross. * Floor position of X after time t : F_{X} = 11 + 57 t * Floor position of Y after time t : F_{Y} = 51 - 63 t 2. Set the two positions equal to find the crossing time: 11 + 57t = 51 - 63t$ 57t + 63t = 51 - 11 $$ 120 t = 40 ⟹ t = \frac{40}{120} = \frac{1}{3} minute 3. Calculate the floor number where they cross: Crossing Floor = 11 + 57 \times (\frac{1}{3}) = 11 + 19 = 30 th floor

Try it yourself before checking the explanation above.

X gets on an elevator at the 11 th floor of a building and rides up at the rate of 57 floors per minute. At the same time, Y gets on an elevator at the 51 st 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?

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