Q39 / 90 · JEE Main 2023 (08 Apr Shift 1) · Mathematics

The number of ways, in which 5 girls and 7 boys can be seated at a round  table so that no two girls sit together is

  • A
    720
  • Correct answer
    B
    126(5!)2
  • C
    73602
  • D
    77202

Solution

Given,

7 boys and 5 girls are to be seated around a circular such that no two girls to be seated together,

Now we know that n objects can be arranged in a circle in (n-1)! ways.

Let us first arrange 7 boys in circular arrangement in 7-1! ways.

Now there will be 7 gaps.

So let us select any 5 gaps out of 7 gaps and arrange 5 girls in the chosen gaps. This can be done in C57×5! ways.

Hence, required arrangements are 6!×C57×5!

=6×5!×7×62×5!

=1265!2.

Therefore, required arrangements are 1265!2

Hence, the correct answer is option: 'B'.

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