Discussion
There are 3 boys and 4 girls in a group. The number of ways they can sit in a row so that between any two boys there is a girl and between any two girls there is a boy, is
Answer: D
The number of ways is 144.
Boys and girls must alternate. With 4 girls and 3 boys in a row of 7, the only alternating pattern is
G B G B G B G
A pattern starting with a boy, B G B G B G, would need as many boys as girls plus one, which fails here. The 4 girls fill their seats in \(4! = 24\) ways and the 3 boys theirs in \(3! = 6\) ways.
\[ 4! \times 3! = 24 \times 6 = 144 \]
The option 288 counts the boy-first pattern as well, which is impossible with these numbers.
No comment is present. Be the first to comment.
Loading…
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development