Question

Six persons A, B, C, D, E and Fare to be seated at a circular table. The number of ways this can be done if A must have either B or C on his right and B must have either C or D on his right, is ______.

• A. 36
• B. 12
• C. 24
• D. 18

Answer 1

The correct option is D 18

Six persons A, B, C, D, E and Fare to be seated at a circular table

Let A,B,C be one unit then no. of ways will be 3!=6

Now A,B,D be one unit then no. of ways will be 3!=6

Now A,C be one unit and B,D be one unit then no. of ways will be 3!=6

$\therefore$ Total no. of possiblities=$6+6+6=18$