If 20 persons are invited for a party then number of different ways the persons and the host can be seated in a circular table, if two particular persons are to be seated on either side of the host is
The correct option is A 2×18!
There are total of 20+1=21 persons.
Let the two particular persons and the host be considered as one single unit.so, the remaining 21−3+1=19 units can be arranged in circular table in 18! ways.
But the two persons on either side of the host can be arranged among themselves in 2! ways. Hence there are 2!×18! ways