Condition: No 2 males are together AND no 2 females are together.
Think - When will this happen? Males and Females must be in alternate positions. Else, at least 2 males (or females) will end up together.
Visualizing the possible scenarios -
_M_M_M_M_M_M_M_M_
The spaces highlighted above is where we can have females. We can have at most one female in any of these spaces.
Given that
number of females >= number of males, here are the possible scenarios ->
(1)
F M
F M
F M
F M
F M
F M
F M
F M _ (8 males and 8 females)
Number of different lineups possible = 8! (ways of placing the males) x 8! (ways of placing the females) = 8! x 8!
(2)
_ M
F M
F M
F M
F M
F M
F M
F M
F (8 males and 8 females)Number of different lineups possible = 8! (ways of placing the males) x 8! (ways of placing the females) = 8! x 8!
(3)
F M
F M
F M
F M
F M
F M
F M
F M
F (8 males and 9 females) Number of different lineups possible = 8! (ways of placing the males) x 9! (ways of placing the females) = 8! x 9!
Final answer = (1) + (2) + (3) = 8! x 8! (1 + 1 + 9) =
8! x 8! x 11. Choice D.---
Harsha