Answer: 9!/(4!3!2!).
- A 9!
- B 9!/(4!3!2!)
- C 4!3!2!
- D 24
Correct answer: B. 9!/(4!3!2!)
Explanation: Multinomial permutation: n=9 total, with groups 4,3,2. Arrangements = 9!/(4!3!2!) = 362880/(24×6×2) = 362880/288 = 1260.
Counting tree for selecting 2 items from {A, B, C} without repetition: 3 x 2 = 6 ordered arrangements.
Concept context
Counting, arrangements, and selections