Question
Download Solution PDFDavid gets on the elevator at the 11th floor of a building and rides up at the rate of 57 floors per minute. At the same time, Albert gets on an elevator 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?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFGiven:
Rate of riding up the floors of David = 57 floors per minute
Rate of riding down the floors of Albert = 63 floors per minute
Floor at which David gets an elevator = 11th floor
Floor at which Albert gets an elevator = 51st floor
Calculation:
Let time taken to cross their paths be ‘t’ minutes
According to the question,
⇒ 11 + 57t = 51 – 63t
⇒ 120t = 51 – 11
⇒ 120t = 40
⇒ t = 40/120
⇒ t = 1/3 minute
Number of floors covered by David in 1/3 minute = 1/3 × 57 = 19
Floor at which their path crossed = 11 + 19 = 30th floor
∴ At 30th floor their paths cross.
Hence, "Option 3" is the correct answer.
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