In the movie Nine Dead, there were 20 people inside a room, in how many ways…
2023
In the movie Nine Dead, there were 20 people inside a room, in how many ways can 10 software engineers and 10 civil engineers be seated around a round table so that they are positioned alternatively?
- A.
9! × 10!
- B.
10! × 10!
- C.
2! × 10!2
- D.
2 × 9! × 10!
Attempted by 7 students.
Show answer & explanation
Correct answer: A
Fix the circular arrangement of the 10 software engineers in 9! ways. The 10 civil engineers can then occupy the 10 gaps between them in 10! ways. Therefore, the number of alternating arrangements is 9! x 10!.