There are 7 friends (A1, A2, A3....A7).If A1 have to have shake with all without repeat. How many handshakes possible?

• I refer TCS placement paper. The correct ans is 6.
  15. There is 7 friends (A1, A2, A3....A7).If A1 have to have shake with all without repeat. How many handshakes possible?
  a) 6
  b) 21
  c) 28
  d) 7
  Solution:6
• 9 years agoHelpfull: Yes(13) No(2)
• 6+5+4+3+2+1=21
• 9 years agoHelpfull: Yes(12) No(6)
• See the question only A1 have to shake hand with others
  So and wud be 6
  If every one have to shake hand with other then=7*6/2=21
• 9 years agoHelpfull: Yes(5) No(4)
• Ans : 6. cause he cannot shake hand with himself and the number of friends are 7 so 7-1=6.
• 9 years agoHelpfull: Yes(3) No(5)
• A1 with 6 persons...
  A2 with 5 person.... so on..
  A6 with 1 person
  so total number of handshakes (6+5+4+3+2+1)=21
• 9 years agoHelpfull: Yes(2) No(0)
• 6+5+4+3+2+1=21
• 9 years agoHelpfull: Yes(1) No(0)
• A1 can shake hands with 6 people, A2-A7
  A2 can shake hands with 5 people, A3-A7
  
  and so on
  If there are n people, there are (n-1)! ways for them to shake hands.
  In this case, 6!=720 ways.
  
• 9 years agoHelpfull: Yes(1) No(0)
• A1 can shake hands with 6 people, A2-A7
  A2 can shake hands with 5 people, A3-A7
  and so on
  If there are n people, there are (n-1)! ways for them to shake hands.
  In this case, 6!=720 ways.
• 9 years agoHelpfull: Yes(1) No(7)
• only A1 have to handshake with all without repeat and not with himself. so the possibility is 6.
  
• 9 years agoHelpfull: Yes(1) No(0)
• 7c2=21=>(7*6)/(1*2)
• 9 years agoHelpfull: Yes(0) No(0)
• If A1 only have shake his hands then the ans is 6. If everyone have to shake, then A1 = 6 handshakes becoz he cant repeat. and remaing 6 friends can shake their hands of 6! = 720. totally 726. I m not sure this is correct.
• 9 years agoHelpfull: Yes(0) No(1)
• obvious ans. is 6
  but if we talk about total no. of handshakes without repeat in 7 persons then it will be 7c2 =21
  because a single handshake need 2 person and poosible no. of pair of two without repetition is 7c2
• 9 years agoHelpfull: Yes(0) No(1)
• if A1have to have shake with all then the ans is 6.
• 9 years agoHelpfull: Yes(0) No(0)
• ans is - 6
  bz only A1 HAVE TO HAVE SHAKE WITH EVERY ONE WITHOUT REPEAT
• 9 years agoHelpfull: Yes(0) No(1)
• For total hand shake = nC2 :where n is no.of people
  here 7C2=[7•6]/2•1=21
• 9 years agoHelpfull: Yes(0) No(0)
• n(n-1)
  7(7-1)=42
  
• 9 years agoHelpfull: Yes(0) No(0)