Statistics - Circular Permutation


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Circular permutation is the total number of ways in which n distinct objects can be arranged around a fix circle. It is of two types.

  1. Case 1: - Clockwise and Anticlockwise orders are different.

  2. Case 2: - Clockwise and Anticlockwise orders are same.

Circular Permutation

Case 1: Formula

${P_n = (n-1)!}$

Where −

  • ${P_n}$ = represents circular permutation

  • ${n}$ = Number of objects

Case 2: Formula

${P_n = \frac{n-1!}{2!}}$

Where −

  • ${P_n}$ = represents circular permutation

  • ${n}$ = Number of objects

Example

Problem Statement:

Calculate circular permulation of 4 persons sitting around a round table considering i) Clockwise and Anticlockwise orders as different and ii) Clockwise and Anticlockwise orders as same.

Solution:

In Case 1, n = 4, Using formula

${P_n = (n-1)!}$

Apply the formula

${P_4 = (4-1)! \\[7pt] \ = 3! \\[7pt] \ = 6 }$

In Case 2, n = 4, Using formula

${P_n = \frac{n-1!}{2!}}$

Apply the formula

${P_4 = \frac{n-1!}{2!} \\[7pt] \ = \frac{4-1!}{2!} \\[7pt] \ = \frac{3!}{2!} \\[7pt] \ = \frac{6}{2} \\[7pt] \ = 3 }$



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