Elevator Weight Limit

To maximize the number of people $n$, we should minimize their weights. There is at least 1 person of weight $57\text{ kg}$ and 1 person of weight $53\text{ kg}$. All other $(n - 2)$ people can weigh at least $53\text{ kg}$. Total weight = $57 + 53 + (n - 2) \times 53 \le 630$ $110 + 53(n - 2) \le 630$ $53(n - 2) \le 520 \implies n - 2 \le 9.81 \implies n - 2 = 9 \implies n = 11$.