17. A large circular table has 60 chairs around it. What is the largest number of people who can sit around the table so that each person is only sitting next to exactly one other person?
A 40
B 36
C 30
D 25
E 20
17. A Since no person can sit next to more than one person, each block of three adjacent seats can contain no more than 2 people. Hence no more than $(60 \div 3) \times 2=40$ people can sit at the table. To show that this is possible, consider twenty groups of three seats around the table with the seats successively occupied, occupied and empty within each block so that every person is sitting next to exactly one other person. Therefore the maximum number of people who can sit around the table is 40 .