19 people(a1,a2......a19)are invited to a party. The host and the
hostess shake hands with each invitee and also with each other. The
invitee shake hands in a circular fashion, i.e. the
pairs(a1,a1),(a2,a3).........(a18,a19),(a19,a1)shake hands. So in all
three are 58 handshakes. Let S be a set of people such that every
pair in S shake hands. The size of S is at most

• The answer is 4.
  Host+ hostess +(a1,a2).
  The last group may also be(a2,a3),etc.
• 13 years agoHelpfull: Yes(12) No(1)
• answer is 3.
  set={{host},{hostess},{invitee}}
• 13 years agoHelpfull: Yes(3) No(2)
• The answer is 9.
• 13 years agoHelpfull: Yes(0) No(6)