WBCS.LIVE practice question

Let,nPr = n(n−1)(n−2)……(n−r+1), where n, r are integers such that 1 ≤ r ≤ n. If ⁿP₄ = 5040, find n.

Solve this multiple-choice question and check the correct answer with its explanation below.

Answer options

  1. 10
  2. 12
  3. 20
  4. 16

Correct answer and explanation

Correct answer: 10

Explanation: ✅ Correct Answer: A) 10 📚 Explanation: The term nP4 represents the product of four consecutive descending integers starting from 'n'. We need to find the number that results in 5040 when multiplied this way. Calculation: 10 x 9 x 8 x 7 = 5040. Therefore, 'n' must be 10. This is a basic math problem involving the principles of permutations.