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

• A1 can shake hand with rest 6 persons
  from 6 person he can select every person to shake hand in 6c1 way and there is no repeatation.
  so, ans is 6c1=6
• 12 years agoHelpfull: Yes(17) No(2)
• A1 shakes hand with remaining persons, total handshakes are 6.
• 12 years agoHelpfull: Yes(4) No(1)
• for linear or without repeat is always n-1=7-1=6
  for circular or with repeat is always n=7
• 12 years agoHelpfull: Yes(2) No(3)
• A1 can shake hand with rest 6 persons.
  Other 6 person to shake hand in 6c2 way (only A1 have shake without repeat, and other 6 person have shake with repetition)
  so, 6c2 + 6=15+6=21
• 9 years agoHelpfull: Yes(2) No(1)
• 6+5+4+3+2+1=21
• 6 years agoHelpfull: Yes(0) No(1)