The number of ways in which 12 different books can be arranged in the book…
2024
The number of ways in which 12 different books can be arranged in the book shelves so that 4 books are together.
- A.
8! X 4!
- B.
9! X 4!
- C.
10! X 4!
- D.
9! X 3!
Attempted by 44 students.
Show answer & explanation
Correct answer: B
Solution:
Treat the 4 books that must be together as a single block. Along with the other 8 individual books, this gives a total of 9 items to arrange.
Arrange these 9 items: there are 9! ways to do this.
Arrange the 4 books within the block: there are 4! ways to order them internally.
Total number of arrangements = 9! × 4! = 8,709,120.