permutation

Question

number of arrangements in which 5 boys and 3 girls are arranged such that at least 2 girls to be separated

Comments

it is 
8! - 6! *3!

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yes i forget to permutate 3 girls amonthemselves

Answer 1

Atleast 2 girls seperated can be written as all permutations - permutations with all girls together

So total ways = 8! - 6! *3!
why 3!because 3 girls can be arranges themselves.
why 6! because all three girls consider it as one group with all five boys giving total of 6!