Question
Question: In how many ways 5 boys and 5 girls can be seated along a line so that they are alternate?...
In how many ways 5 boys and 5 girls can be seated along a line so that they are alternate?
A
5!5!
B
! 5 !
C
2 x 5! X 5!
D
5! 4!
Answer
2 x 5! X 5!
Explanation
Solution
The two possibilities are
(i) B1 x B2 x B3 x B4 x B5 x
(ii) G1 x G2 x G3 x G4 x G5 x
5 boys are arranged at 5 places in 5! Ways. For girls, 5 places are left, in which they can be placed in 5! ways. In case (2) boys and girls have changed their position.
∴ Required ways = 2 (5 ! x 5 !)