22. 36 people {a1, a2, ., a36} meet and shake hands in a circular fashion. In
other words, there are totally 36 handshakes involving the pairs, {a1, a2}, {a2, a3},...., {a35, a36}, {a36, a1}. Then size of the smallest set of people such that the rest have shaken hands with at least one person in the set is

12
13
18
11

• 12 persons in the set.
  a2 has shaken hands with a1 and a3.
  a5 has shaken hands with a4 and a6.
  
  so a2,a5,a8.........a35 .... total 12 persons.
• 13 years agoHelpfull: Yes(7) No(2)
• 36/3=12
  as in a group of 3 people other 2 have made at least 1 handshakes with him....
  means a1,a4,a7,a10,a13,a16,a19,a22,a25,a28,a31,a34.....
  here every others had make at least one handshakes with these people......
• 13 years agoHelpfull: Yes(3) No(2)