How many permutations of 7 objects taken 2 at a time are there?
Answer and explanation
Correct answer: C.
- Step 1: P(n, r) = n!/(n − r)!. Step 2. P(7, 2) = 42. **Answer: . Why not the others:** is what you get if you count combinations. is what you get if you multiply n by k. is what you get if you allow repetition.
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