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If there are 12 persons in a party and each of them shakes hands with each other, how many handshakes do happen in the party?
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- 77
- 66
- 44
- 55
Correct Option: B
first person will shake hands with 11 other persons. Seconds person will shake hands with 10 other persons, Third person will shake hands with 9 other person and so on.
So , total handshake
= 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 = 66
OR
2 person are to be chosen from 12 person to have a hand shake
∴ Possible ways = 12C2 = 12! / 2!(12 - 2)! = 66
