Question

A person climbs up a stalled escalator in $60\, s$ . If standing on the same but escalator running with constant velocity he takes $40\, s$. How much time is taken by the person to walk up the moving escalator ?

• A. 37 s
• B. 27 s
• C. 24 s
• D. 45 s

Answer 1

Answer: (C)

24 s

Answer 2

$60=\frac{d}{v_{\text{man}}}$
$40=\frac{d}{v_{e s}}$
$t=\frac{d}{v_{\text{man}}+v_{e s}}$
$\frac{1}{t}=\frac{v_{\text{man}}}{d}+\frac{v_{e s}}{d}=\frac{1}{60}+\frac{1}{40}$
$t=24 \sec$