12 persons can arrange themselves around the table in (12-1)!=11!;ruplun wrote:If '12' persons are seated at a round table, what is the probability that two particulars persons sit together?
as two particular persons sit together consider them as a one group, therefore we have 11 people to arrange around the round table which can be done in (11-1)!=10! also two particular person can exchange positions among themselves in 2! ways, hence required probability is 10!*2!/11!=2/11;
