+0  
 
-2
105
2
avatar+-291 

Five couples were at a party. If each person shook hands exactly once with everyone else except his/her spouse, how many handshakes were exchanged? (Note: One obviously doesn't shake hands with oneself.)

 Mar 28, 2020
 #1
avatar+4568 
+1

All ten people shake hands with everyone except his/jher spouse and themseves.

 

 

Since there are 10 people(five(5) married couples), the answer should be 10 * 8  /  2  = 40 handshakes were exchanged,

 

Note that dividing by two cleared the overcounting of the handshakes.

 Mar 28, 2020
 #2
avatar+111330 
+1

I get a little different result  from tertre

 

Note  that   the

 

10th person    shakes  9  hands

9th person      shakes  8  hands

8th person      shakes  7  hands

   .....

2nd person     shakes  1   hand

 

So.....the  number of handshakes  seems just to be  the  sum of the  first 9 positive integers =

 

9 * 10  / 2    =     45 handshakes 

 

 

cool cool cool

 Mar 28, 2020

6 Online Users