Answer: n!/p!.
- A n!/p!
- B n! × p!
- C p!/n!
- D (n-p)!
Correct answer: A. n!/p!
Explanation: When p items are identical: permutations = n!/p!. Divides by repetitions.
Counting tree for selecting 2 items from {A, B, C} without repetition: 3 x 2 = 6 ordered arrangements.
Concept context
Counting, arrangements, and selections