There are 13 couples, 5 single men and 7 single women in party. Every man shakes hand with every woman once. But none shakes hand with his wife. How many handshakes in total took place in the party?
347
There are 13 couples: 13 men & 13 women In addition to it, there are 5 single men and 7 single women Now, 5 single men can shake hands with 20 women, therefore 5*20 = 100 ways Also, each of 13 males (from the couples) can shake hands with 12 women (except his wife) + 7 single women. So 13 * 19 = 247 ways. Therefore, in total 347 ways