9 handshakes if everyone shakes everyones hand once
Depends what you mean, if you mean if everyone shakes hands just once then N-1 handshakes are made. If you mean if everyone shakes hands with everyone else then the answer is (N-1)+(N-2)+....+2+1 (we dont include N as they're not going to shake their own hand, obviously) written as Σn-1i=1 i, this is a arithmetic progression and so the total number of handshakes will be equal to (1+(n-1))(n-1)/2
if there are 2 people in a room and each one shakes hands once with every other person in the room, how many hand shakes are there?... answer( 1 handshake) pretty easy isn't it? if there are 3 people in a room and everyone shakes hands with everyone else, how many hand shakes are there? answer( three handshakes) now how many handshakes will there be for 5 people in a room? its your time to shyne...
4*3/2 = 6 handshakes.
9 handshakes correct answer is 10
Everyone shakes hands with 4 other people. Since there are 5 people in the room this would suggest there are 5*4 = 20 handshakes. However, you would then be double counting handshakes: A shaking hands with B and B shaking hands with A is, in reality, only one handshake. Thus there are 5*4/2 = 10 handshakes in all.
If there are seven people, then the number of handshakes is 7*6/2 = 21
There will be 28 handshakes. If you ask each person how many handshakes they had they will tell you 7 making 7 x 8 = 56 handshakes in all. But every hand involves two people, so every handshake has been counted twice, thus there are 56 / 2 = 28 handshakes in all.
If that happens you have to times ninexten and the answer would be 90 handshakes