Question

It takes one minute for a passenger standing on an escalator to reach the top. If the escalator does not move it takes him 3 minutes to walk up. How long will it take for the passenger to arrive at the top if he walks up the moving escalator?

• A. $30sec$
• B. $45sec$
• C. $40sec$
• D. $35sec$

Answer 1

Answer: (B)

$45sec$

Let the distance to the top be d.

therefore the speed of the man with escalator not moving $=\left(\frac{d}{1}\right)m/min$

therefore the speed of the escalator with the man at rest$=\left(\frac{d}{3}\right)$m/min

when both the main and the escalator are moving, effective speed$=(\frac{d}{3}+d)$ m/min

$=\frac{4d}{3}$ m/min

Therefore time taken when both men and escalator are moving$=\frac{distance}{speed}=\frac{d}{\frac{4d}{3}}$

$\frac{3}{4}min=45$seconds

Hence (B) is correct answer