Question 5
A museum has four floors. Each floor has seven rooms numbered 1–7 and doors connecting some rooms, as shown. In the diagrams, “Tầng” means floor, “Cửa vào” means entrance and “Lối ra” means exit.
On how many floors can a visitor enter, visit every room exactly once, and then leave through the exit?
On how many floors can a visitor enter, visit every room exactly once, and then leave through the exit?