Question

A lift descends into an underground floor at the rate of 6 metres per minute. If the descend starts from 10 metres above the ground level, how much time will it take to descend 350 metres underground?

• A. 30 minutes
• B. 50 minutes
• C. 1 hour
• D. 1 hour 30 minutes

Answer 1

The correct option is C

1 hour

The lift has to descend 360 m so as to reach -350 m, as it is 10 m above the ground level.
Given that the lift descends at the rate of 6 m/minute.
Given that to decend 6 m $\to$ lift takes 1 minute
$\Rightarrow$ To decend 360 m $\to$ lift takes $\frac{360}{6}$= 60 minutes = 1 hour
$\therefore$ The lift will take 1 hour.