Tulip wrote:

1) For 2 people there is 1 handshake

For 3 people there is 3 handshakes

Can you predict the number of handshakes for 10,15,20 people?

Can you work out a formula ?

2) 3 monkeys and their partners are invited to a party.When they reach the

party everyone shakes hands with everyone except their own partners.

How many handshakes were there?

How many hands shakes would there be for 4 monkeys and their partners?

5 monkeys?

Can you predict the number of handshakes for 10,15,20 monkeys and their

partners?

1) If there are N people, each one shakes hands with the remaining N-1 people. There are 2 people in each handshake, so divide by 2, giving N*(N-1)/2.

2) There are 2N monkeys, each shaking hands with 2N-2 monkeys. Again divide by the number of monkeys in each handshake (2), giving 2N*(2N-2)/2 = 2N*(N-1).