3. Why did they go up to their room?

Решение:

В тексте сказано: "The friends got a room on the forty-fifth floor." Так как лифт не работал, им пришлось идти вверх, чтобы попасть в свой номер.

Ответ: They went up to their room because they had a room on the forty-fifth floor and the lift was not working.