Question

How many ways 9 members can have a sitting arrangement if they sit arround a round table and the secretary and the president always sit together.

Answer 1

Hi!

Here is the answer to your question.

Considering the secretary and the president who sit together as one person, we have only 7 + 1 = 8 persons. These 8 persons can be seated around a round table in 8! ways.

(Number of ways in which n different things can be arranged along a circle = (n – 1)!)

But the secretary and the president can be arranged among themselves in 2! ways.

∴Total numbers of sitting arrangements = 8! × 2! = 40320 × 2 = 80640. (Multiplication principle of counting)

Cheers!