Question

Find the number of ways in which 5 boys and 5 girl be seated in a row so that (i)No two girls may sit together (ii)All the girls sit together (iii)all the boys sit together. (iv)All the girls are never together.

Answer 1

Number of girls sit together`=.^6C_5*5!*5! =6(5!)^2`
All the girls never sit together`=10!-6(5!)^2`.