1.

Thirteen guests have participated in a dinner. The number of handshakes that happened in the dinner is: (a) 715 (b) 78 (c) 286 (d) 13 (b) 78

Answer»

(b) 78

To handshakes, we need two guests. 

Number of selecting 2 guests from 13 is 13C2

\(\frac{13\times12}{2\times1}\) = 78



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