[quote="akadiyan"]At a dinner party, 8 students (Hermione, Ron, Fred, George, Neville, and 3 Beauxbatons students) are to be seated around a circular table. 2 seating arrangements are considered different only when the positions of the people are different relative to each other. What is the total number of different possible seating arrangements for the group if the 3 Beauxbatons students insist on sitting next to each other and Hermione and Ron insist on sitting apart?
Arrangement around a circular table = (N-1)!
Total arrangement:
{George}, {Fred}, {Neville}, {Hermione , Ron} , {B1} , {B2} , {B3}
Now we have 7 units and can be arranged in a circular table in (7-1)! = 6! # of ways =
720 ways
Restriction:
1.Hermione and Ron insist on sitting apart.
2.Three Beauxbatons students insist on sitting next to each other.
Arrangement with restriction looks like
{George}, {Fred}, {Neville}, {Hermione , Ron} , {B1, B2, B3}
We have 5 units, so total arrangements = (N-1)! = 4! = 24 ways
Hermione and Ron can be arranged in 2 ways
Beauxbatons can be arranged in 6 ways
Number of arrangements with restriction = 24*2*6 =
288 Total number of arrangements:
The total number of arrangements = {Total} - {Restriction} = 720 - 288 =
432Ans:
D[/quote
Kindly clarify why you take total arrangement as 6!. Given there are 8 students, shouldn't the total arrangement be 7!?