cars in Mexico city - All-Russian MO 1997 Regional (R4) 8.8
Source:
September 23, 2024
combinatorics
Problem Statement
In Mexico City, to limit traffic flow, each private car is set two days of the week on which it cannot go out onto the city streets. A family needs to have at least 10 cars at its disposal every day. What is the smallest number of cars can get by with the seven if its members can choose forbidden days for your cars?