You walk upwards on an escalator, with a speed of 1 step per second. After 50 steps you are at the end. You turn around and run downwards with a speed of 5 steps per second. After 125 steps you are back at the beginning of the escalator. How many steps do you need if the escalator stands still?
Let v be the speed of the escalator, in steps per second. Let L be the number of steps that you need to take when the escalator stands still. Upwards (along with the escalator), you walk 1 step per second. You need 50 steps, so that takes 50 seconds. This gives: L - 50 ?v = 50. Downwards (against the direction of the escalator), you walk 5 steps per second. You need 125 steps, so that takes 25 seconds. This gives: L + 25 ?v = 125. From the two equations follows: L = 100, v = 1. When the escalator stands still, you need 100 steps.. Source: CoolInterview.com
say the escalator moves x steps in each second.thus if i move with 1 step/sec and taked 50 secs then steps taken by me=50. total steps i moved =50 +50x
now when i come down stepa taken by me =125 time i take to come down=125/5=25secs in this time steps taken by escalator=25x
now since the escalator is same then total number of steps would be same hence 50+50x=125-25x thatgives x=1 thus escalator moves 1 step upwards each second thus when i move 50 steps up escalator also moves 50 steps up and i reach at the top hence totalnumber of steps i have to climb to reach the top when escalator is not there=100 Source: CoolInterview.com
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