Question 176
In an apartment building with floors $0$ up to and including $10$, there is one person living on each floor. Each morning, everyone in the building must go to floor $0$ to go outside. Everyone is willing to walk the stairs for at most three floors. There can be at most four people in the lift at the same time. The lift starts at floor $0$.
At least how many floors must the lift move to get everyone outside? Movements up and movements down are both counted.
At least how many floors must the lift move to get everyone outside? Movements up and movements down are both counted.