A person walks up a stalled excalator in 90 sec. When standing on sam...
Problem Statement
A person walks up a stalled escalator in 90 seconds. When standing on the same escalator now moving, he is carried in 60 seconds. Find out the time he would take to walk up the moving escalator.
Solution
Understanding the Problem
In this problem, we need to find out how long the person will take to walk up a moving escalator. We are given two pieces of information:
- The person takes 90 seconds to walk up a stalled escalator.
- The person is carried by the escalator in 60 seconds when it is moving.
Calculating the Speed of the Person and the Escalator
To solve this problem, we first need to calculate the speed of the person and the escalator when they are moving together and when they are moving in opposite directions. We can do this using the following formulas:
- Speed of the person = Distance / Time taken
- Speed of the escalator = (Distance covered by the person + Distance covered by the escalator) / Time taken
Let's assume that the distance covered by the person is D, and the distance covered by the escalator is E.
Calculating the Speeds when Moving Together and in Opposite Directions
When the person and the escalator are moving together, their speeds are added up. So:
- Speed of the person and the escalator when moving together = (D + E) / 60
When the person and the escalator are moving in opposite directions, their speeds are subtracted. So:
- Speed of the person when moving up the escalator = (D - E) / t, where t is the time taken by the person to walk up the moving escalator
Using the Given Information to Solve for t
From the given information, we know that:
- Speed of the person and the escalator when moving together = Speed of the person when moving up the escalator + Speed of the escalator
- The person takes 90 seconds to walk up a stalled escalator, which means that the distance covered by the person is equal to the length of the escalator.
Using these two equations, we can solve for t:
(D + E) / 60 = (D - E) / t + E / 60
Substituting D = length of the escalator:
(E + length of the escalator) / 60 = (E - length of the escalator) / t + E / 60
Simplifying:
t = 2 * length of the escalator / (E + length of the escalator)
Calculating the Value of t
To calculate the value of t, we need to find out the value of E. We know that the person takes 60 seconds to be carried by the escal