Question:

The number of ways in which $5$ ladies and $7$ gentlemen can be seated in a round table so that no two ladies sit together, is

Updated On: Jun 22, 2024
  • $ \frac{7}{2}{{(720)}^{2}} $
  • $ 7{{(360)}^{2}} $
  • $ 7{{(720)}^{2}} $
  • $ 720 $
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The Correct Option is A

Solution and Explanation

First we fix the alternate position of 7 gentlemen in a round table by 6! ways. There are seven positions between the gentlemen in which 5 ladies can be seated in $ ^{7}{{P}_{5}} $ ways.
$ \therefore $ Required number of ways
$=6!\times \frac{7!}{2!} $
$=\frac{7}{2}{{(720)}^{2}} $
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Concepts Used:

Permutations

A permutation is an arrangement of multiple objects in a particular order taken a few or all at a time. The formula for permutation is as follows:

\(^nP_r = \frac{n!}{(n-r)!}\)

 nPr = permutation

 n = total number of objects

 r = number of objects selected

Types of Permutation

  • Permutation of n different things where repeating is not allowed
  • Permutation of n different things where repeating is allowed
  • Permutation of similar kinds or duplicate objects