Engineering Board Exam Reviewer · Circular and Cyclic Permutations · hard

In how many ways can 5 married couples be seated around a round table if each husband must sit next to his wife?

  1. 768
  2. 3,840
  3. 48
  4. 2,880

Answer

A. 768

Solution

Treat each couple as a unit: 5 units around the table in (5-1)!=24 ways. Each couple can be arranged internally in 2 ways, so multiply by 25=32. Total =24×32=768.

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