Moody takes 30 seconds to finish riding an escalator if he walks on it at his normal speed in the same direction. He takes 20 seconds to finish riding the escalator if he walks at twice his normal speed in the same direction. If Moody decides to stand still on the escalator, then the time, in seconds, needed to finish riding the escalator is
Explanation:
Let speed of Moody and escalator be ‘m’ and ‘e’ steps/sec and total number of steps in the escalator be ‘N’.
We will assume that Moody is going in the same direction as the escalator. If that is not the case value of e will come out to be negative.
Moody takes 30 seconds at normal speed ⇒ N = 30m + 30 ×e …(1)
Moody takes 20 seconds at twice the speed ⇒ N = 20 × 2m + 20 ×e …(2)
4 × (1) – 3 × (2) N = 60e ⇒ N/e = 60
∴ If someone was standing on the escalator, he/she will take 60 seconds to climb the escalator.
Hence, 60.
Concept: Escalators
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