Q.

The number of ways, 5 boys and 4 girls can sit in a row so that either all the boys sit together or no two boys sit together, is __________.          [2025]


Ans.

(17280)

Number of ways that all boys sit together =5!×5!

Number of ways no two boys sit together =4!×5!

   Required number of ways =5!×5!+4!×5!=17280