1. In a residential building, there are four apartments. In the first one, a three-member family lives, in the second and third, four-member families, and in the fourth, a five-member family. The joint bill for the maintenance of the building is divided in the ratio of the number of family members. What percentage of the amount on the bill should each family pay?
1. The total number of people sharing the maintenance costs is 16.

Each person bears $1: 16=6.25\%$ of the costs. 1 POINT

A three-member family pays $18.75\%$ of the total cost, 1 POINT

four-member families pay $25\%$ of the total cost each, 1 POINT

and a five-member family pays $31.25\%$ of the cost. 1 POINT

TOTAL 4 POINTS