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Eighteen guests are to be seated, half on each side of a long table. Four particular guests desire to sit on one particular side and three others on other side of the table. The number of ways

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Question

Eighteen guests are to be seated, half on each side of a long table. Four particular guests desire to sit on one particular side and three others on other side of the table. The number of ways in which the seating arrangements can be made is `(11!)/(5!6!) (9!)(9!)`.

Options

  • True

  • False

MCQ
True or False
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Solution

This statement is True.

Explanation:

When 4 guests sit can one side and 3 on the other side

We have to select out of 11.5 sit one side and 6 sit on the other side.

Now, remaining selecting on one half side = `""^(18 - 4 - 3)"C"_5`

And the other half side = `""^((11 - 5))"C"_6` = 6C6

So, the total arrangements = 11C5 × 9! × 6C6 × 9!

= `(11!)/(5!6!) xx 9! xx 1 xx 9!`

= `(11!)/(5!6!) (9!)(9!)`

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Chapter 7: Permutations and Combinations - Exercise [Page 127]

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NCERT Exemplar Mathematics Exemplar [English] Class 11
Chapter 7 Permutations and Combinations
Exercise | Q 57 | Page 127

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