Thirty people are in a room and each person shakes hands exactly once with everyone else. How many handshakes will take place.
I think there is a formula for this involving "!" but cant remember it. Any other ways?
2007-10-01 05:42:47 · 2 answers · asked by ogarcia_02 2 in Education & Reference ➔ Homework Help
If there are two people, they can shake hands with each other only once.
If there are three, they can shake hands with each other this way:
A to B, A to C, B to C - 3 times.
And if four people are there, ABCD, we have
AB, AC, AD, BC, BD, CD - 6 times.
So, if we have 30 people, we have
29 + 28 + 27 + ...
So, it is an Arithmetical Progression of n-1 terms.
S n-1 is the answer.
2007-10-01 05:54:55 · answer #1 · answered by Swamy 7 · 2⤊ 0⤋
i think its 30x30=900 handshakes
2007-10-01 06:05:38 · answer #2 · answered by Vicki D. 3 · 0⤊ 1⤋