Given that, Weight limit of elevator $ = 630\;\text{kg}$
- The lightest person's weight $ = 53 \;\text{kg}$
- The heaviest person's weight $ = 57 \;\text{kg}$
We can write, $ 53 + \underbrace{\ldots \ldots}_{\text{Weights of $n$ people}} + 57 = 630$
In order to have maximum people in the lift, all the remaining people should be of the lightest weight possible, which is $ 53 \;\text{kg}.$
Suppose there are $n$ people in the elevator.
Then, $53 + n(53) + 57 < 630$
$ \Rightarrow 53n < 520$
$ \Rightarrow n < \frac{520}{53}$
$ \Rightarrow n < 9.811 $
$\Rightarrow n_{\text{max}} = \left \lfloor 9.811 \right \rfloor$
$\Rightarrow n_{\text{max}} = 9$
$\therefore$ The maximum number of people in the group $ = n_{\text{max}} + 2 = 9 + 2 = 11.$
Correct Answer $: \text{C}$