SATHEE: Permutations And Combinations Question 7

Permutations And Combinations Question 7

Question: 20 persons are invited for a party. In how many different ways can they and the host be seated at a circular table, if the two particular persons are to be seated on either side of the host [IIT 1977]

Options:

A) $ 20\ ! $

B) $ 2\ .\ 18\ ! $

C) $ 18\ ! $

D) None of these

Show Answer

Answer:

Correct Answer: B

Solution:

There are 20 + 1 = 21 persons in all. The two particular persons and the host be taken as one unit so that these remain 21 - 3 + 1 = 19 persons to be arranged in 18 ! ways. But the two person on either side of the host can themselves be arranged in 2! ways. Hence there are 2 ! 18 ! ways or $ 2.18! $ ways.

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Permutations And Combinations Question 7

Question: 20 persons are invited for a party. In how many different ways can they and the host be seated at a circular table, if the two particular persons are to be seated on either side of the host [IIT 1977]

Options:

Answer:

Solution:

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