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WAEC Further Mathematics 2011 Question 30

Question 30

Permutations and Combinations

Four doctors and two nurses are to sit round a circular table. In how many ways can this be done if the nurses are to sit together?

  1. A.48
  2. B.60
  3. C.240
  4. D.720
Show the answer and explanation

Answer: A (48)

Explanation

Tie the two nurses together as one unit: 5 units round a table can sit in 4! = 24 ways, and the nurses can swap places in 2 ways. 24 × 2 = 48.