Gujarati
6.Permutation and Combination
easy

Everybody in a room shakes hand with everybody else. The total number of hand shakes is $66$. The total number of persons in the room is

A

$11$

B

$12$

C

$13$

D

$14$

Solution

(b) $^n{C_2} = 66 \Rightarrow n(n – 1) = 132 \Rightarrow n = 12$.

Standard 11
Mathematics

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