CA Foundation · Quantitative Aptitude · Permutations and Combinations
If nP2 = 90, what is the value of n?
The value of n is 10. The permutation nP2 equals n×(n−1), so we need two consecutive integers whose product is 90. Since 10×9 = 90, n must be 10. Testing n = 9 gives only 72, which does not match.
- A8
- B9
- C10Correct
- D11
Explanation
nP2 = n(n−1) = 90. Since 10×9 = 90, n = 10. Option 9 would give 9×8 = 72, which is a result of misreading the factors.
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