Question

12 persons are to be arranged to a round table. If two particular persons among them are not to be side by side, the total number of arrangements is

• A. $9(10!)$
• B. $2(10!)$
• C. $45(8!)$
• D. $10!$

Answer 1

Answer: (A)

$9(10!)$

Arrangements of 12 persons $=11!$

2 persons can not seat together

$\begin{array}{c}=11!-10!2\\ 10!\left(11-2\right)=9\left(10!\right)\end{array}$