Question

Einstein walks on an escalator at a rate of 5 steps per second and reaches the other end in 10 seconds. While coming back, walking at the same speed he reaches the starting point in 40 seconds. What is the number of steps on the escalator?

• A. 40
• B. 60
• C. 120
• D. 80

Answer 1

The correct option is D 80

Let there be l steps in the escalator and x be the speed (in steps/second) of escalator, then
$\frac{I}{(5+x)}=10$ and $\frac{I}{(5-x)}=40$
then $\frac{5+x}{(5-x)}=\frac{40}{10}\Rightarrow x=3$
$\therefore$ Number of steps in the escalator = l = 8 $\times$ 10 = 80