i know that we have to use permutation and combination, but i have forgot them.. (last learnt on my 12th).. need answer with some explanation..
Even I have forgotten.. I had solved this by trial and error method.
For simplicity, assume only 4 people, A, B, C,D, have done handshakes. so total no. of handshakes=AB+AC+AD+BC+BD+CD
..
Similarly if 5 people, total no. of handshakes=AB+AC+AD+AE+BC+BD+BE+CD+CE+DE
.
.
From above two, total no. of handshakes of 'n' people= addition of first (n-1) numbers.
..
So answer is 12
Today's Question:
.
.
Answer will be posted tomorrow.