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At a party , everyone shook hands with everybody else. There were 66 handshakes . How many people were there in the party ?

dsuc.created: 7 years ago | dsuc.updated: 4 years ago
dsuc.updated: 4 years ago
Bangladesh Bank Bangladesh Bank - Assistant Director - 2012 গণিত বিন্যাস (Permutation)
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913
common.best_ans:
Let the number of people be x
For a handshake we need 2 people so selecting 2 person form x can be done in xC2 ways.
Therefore xC2 = 66
x!/(x - 2)!2! = 66
x(x - 1)/2 = 66
x(x - 1) = 132
Solving this we get x = 12
7 years ago
Md Azizur Rahman
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MD.YELIAS
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Eusuf

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