Q. The number of ways in which seven persons can be arranged at a round table, if two particular persons may not sit together is
A) 480
B) 120
C) 80
D) None of these
Explanation
(a)
$\because$ Remaining 5 can be seated in $4!$ ways.
Now, on cross marked five places 2 person can sit in $\ ^{5}P_{2}$ ways
[image:7_image5.emf]
So, number of arrangements
$= 4! \times \frac{5!}{3!}$
$= 24 \times 20 = 480\$ ways
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.