Five oys and three girls are sitting in a row of `8` seats. Number of ways in which they can be seated so that not all the girls sit side by side is
A. `36000`
B. `9080`
C. `3960`
D. `11600`
Correct Answer - A
`(a)` Total no. of arrangement if all the girls do not seat side by side
`=["all arrangement"-"girls seat side by side"]`
`=8!-(6!xx3!)`
`=6!(56-6)=6!xx50`
`=720xx50=36000`
Correct Answer - `(5)/(7)`
Total number of ways is `7!` Favorable number of ways is `7! - 2 (6!)`. Hence, the probability is
`(7! - 2(6!))/(7!) = 1 - (2)/(7) =...
Correct Answer - D
Three-digit numbers are 100, 101, …, 999. Total number of such numbers is 900. The three-digit numbers (which have all same digits) are 111, 222, 333, …,...
Correct Answer - A
Total number of cases = `5!`
Since `S_(1)` gets seat `R_(1)` and none of the other gets previously allotted seat, we have derangement of 4 students. So,...
Correct Answer - A
`(a)` First arrange `12` persons `A_(4),A_(5),….A_(15)` in `"^(15)P_(12)` ways
There remains `3` places. Keep `A_(1)` in the first place and arrange `A_(2)`, `A_(3)` in the remaining two...
Correct Answer - C
`(c )` First arrange `8` blue alike bottles `to ` number of ways `=1`
Now select one gap out of `9` gaps created to put two green...
Correct Answer - C
`(c )` Case I : When no box remains empty
Then number of ways of distribution is `.^(10-1)C_(5-1)=^(9)C_(4)=126`
Case ii : Exactly one box is empty
Number...