CAT Question Bank  Escalators (Time, Speed & Distance)

Q6) An escalator is moving at 3 steps per second. Harish walks in the same direction as moving escalator at 2 steps per second takes 3 second less to get out of the escalator than when he was moving on the stationary escalator. How many steps are there in the stationary escalator?

When moving with escalator
Steps covered per sec = 3 + 2 = 5
when moving in stationary escalator
steps covered per sec = 2
Let the total steps = X
X/2  X / 5 = 3
X = 10
[credits: Abhishek Dangayach]

Q7) Mr. Perumal decided to walk down the escalator of a tube station. He found that if he walks 26 steps, he requires 30 s to reach the bottom. However, if he walks 34 steps he would only require 18 s to reach to the bottom. If the escalator is moving downwards, find the number of steps in the escalator

26 + 30e = 34 + 18e
12e = 8
e = 2/3
26 + 20 = 46

Q8) Mohit moves with a constant speed of 3 steps/second and Sonal moves with a constant speed of 1 step/second on an escalator. When the escalator moves downward at a constant speed, Mohit takes 90 steps while Sonal takes 60 steps to reach the bottom from the top of the escalator. How many steps would be visible in the escalator when it becomes stationary?
(a) 100
(b) 120
(c) 150
(d) 160

Q9) A woman is walking down a downward moving escalator and steps down 10 steps to reach the bottom. Just as she reaches the bottom a sale commences on the floor above. She runs back up on the downward moving escalator at a speed five times that which she walked down. She covers 25 steps in reaching the top. How many steps are visible on the escalator when it is switched off ?

We have given his speeds
so let his earlier speed be 1 step/minute and speed of escalator be x.
So time taken to walk 10 steps is 10 mins
Case 1) 10 + 10x
Case 2) His speed increases by 5 times so new speed becomes 5 steps/ min and time taken is 5 mins
25  5x
10 + 10x = 25  5x
x = 1
total stairs = 20
[Credits : Shweta Arora]

Q10) Rahul & Ajay walk up an escalator which is moving at a constant speed. Rahul takes 2 steps for every 4 steps of Ajay. Ajay takes 20 steps while Rahul takes 12 steps to reach the top. Find how many visible steps are there on the staircase?

20 + 5e = 12 + 6e
e = 8
Total steps = 20 + 5 x 8 = 60

Q11) A man can walk up in a moving escalator in 30 s. The same man can walk down this moving up escalator in 90s. Assume that this walking speed is sane both upwards and downwards. How much time will he take to walk up the escalator when it is not moving ?

Shyama = 3
Ramesh = 2
25 + 25e/3 = 20 + 10e
e = 3
Total steps : 20 + 10 x 3 = 50

Speed of man = x steps/min,
Speed of escalator = n steps/min up only.
In 30 secs,
Total steps upward = (x+n)/2 steps
In 90 secs downwards = (xn)*3/2 steps
These two steps count should be equal.
x = 2n
Time taken= 45 secs
[credits: Rohit Kumar Pandey]

Q12) A person, A, starts descending from the first floor of a building to the ground floor on a descending escalator, while another person, B, simultaneously starts ascending from the ground floor of the building to the first floor, using the same escalator. If the speed of B is twice that of A, and A and B take 30 steps and 120 steps to reach their respective destinations, find the number of steps that are visible on the escalator when it is stationary.

Let A = 1 step/min
B = 2 steps/min and the speed of escalator = e
30 + 30e = 120  60e
90e = 90
e = 1step/min
Total steps = 30 + 30 x 1 = 60
[credits : Shivam Agrawal]

Q13) A man can walk up a moving "Up" escalator in 30 sec. The same man can walk down this moving "Up" escalator in 90 sec. assume that his walking speed is same upwards and downwards. How much time will he talk to walk up the escalator when its not moving ??
a) 30
b) 45
c) 60
d) 90
e) None of these

Let escalator moves up with a speed of E steps per sec and man moves with a speed of 1 step per sec
when both are moving up
S = (E+1)
T = 30
So D = 30 (E+1)
Now when man moves down on up moving escalator
S= (1E)
T = 90
D= 30(E+1)
on solving E = 1/2 steps per sec
D= 45

Q14) Two persons A and B are walking down an escalator in the direction of the motion of the escalator. The ratio of the speeds (in steps) of A and B is 2 : 1 respectively. A covers 60 steps to get out of the escalator and B takes 40 steps to do the same. Find the number of steps in the escalator when it is stationary?
a) 80
b) 90
c) 120
d) 150

When A takes 60 steps, let Escalator takes x steps.
Total no. of steps on a stionary esc = x + 60.
so B will take 30 Steps since Speed is half.
So when B takes 40 steps Escalator should take 4/3x steps.
4/3x + 40 = x+60 and hence x = 60
Ans = 120

Q15) There is an escalator going up from the ground floor to the first floor. Raghu is climbing up the escalator while Rajan is climbing down (from the first floor to the ground floor) on the same escalator. On a stationary escalator, the time taken by Rajan to climb 8 steps is same as the time taken by Raghu to climb 6 steps. On the moving escalator, if Raghu takes 18 steps to reach the first floor while Rajan takes 60 steps to reach the ground floor, how many steps are there on the escalator?
a) 24
b) 30
c) 36
d) 48

d18/t1 = (60d)/t2
60/t2/(18/t1) = 4/3
hence t1/t2= 2/5
so 5d  90= 120  2d
so 7d = 210
d = 30
[credits : Biswanath Chakraborty]