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JEE MATHEMATICS MCQ: PERMUTATIONS

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The number of ways in which 20 different pearls of two colours can be set alternately on a necklace, there being 10 pearls of each colour, is

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Correct option: B

5 \times {\left( {9!} \right)^2}

Option B (

5 \times {\left( {9!} \right)^2}

) is correct because it accounts for arranging the pearls of one color in a circle and then arranging the pearls of the other color in the spaces.

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