CMA Foundation · Fundamentals of Business Mathematics and Statistics · Permutation and Combinations
If (n+1)! = 30 × (n-1)!, what is n?
The value of n is 5. Dividing both sides by (n-1)! gives (n+1)n = 30, which is 6 × 5, so n = 5. Verification: 6! = 720 equals 30 × 4! = 30 × 24 = 720.
- A5Correct
- B6
- C4
- D29
Explanation
(n+1)!/(n-1)! = (n+1)n = 30. Since 6 × 5 = 30, n = 5. Check: 6! = 720 and 30 × 4! = 720. Option 6 would give 42.
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