Mr Ali decided to walk down the escalator of a tube station. He found that if he walks down 26 steps, he requires 30 seconds to reach the bottom. However, if he steps down 34 stairs he would only require 18 seconds to get to the bottom. If the time is measured from the moment the top step begins to descend to the time he steps off the last step at the bottom, find out the height of the stair way in steps?
সমাধান
সঠিক উত্তর: Option C
Let the staircase have n steps
Now, Mr Shah covers n - 26 steps in 30 seconds and n - 34 steps in 18 seconds. Assuming that Mr Shah's speed in either case is same, we have (n - 26)/30 = (n - 34)/18 18n - 18*26 = 30n - 30*34 12n = 30*34 - 18*26 n = 552/12 n = 46 steps
