CA Foundation · Quantitative Aptitude · Permutations and Combinations
If nC2 = 66, what is the value of n?
The value of n is 12. From nC2 = n(n-1)/2 = 66 we get n(n-1) = 132, which equals 12 × 11. Hence n = 12, and 12C2 = 66 confirms it.
- A11
- B12Correct
- C13
- D14
Explanation
nC2 = n(n-1)/2 = 66, so n(n-1) = 132 = 12×11, giving n = 12. Check: 12C2 = 66. Option 11 would give 55, and 13 would give 78.
Did you get it right without looking?
One question tells you little. A timed set on Permutations and Combinations shows your real accuracy, how long you take and where you lose marks.
More Permutations and Combinations questions
- A Chennai firm has 7 chartered accountants and 5 company secretaries. A team of 4 members with exactly 2 chartered accountants and 2 company…
- Six directors of a company in Pune are to be seated around a circular table for a board meeting. In how many distinct ways can they be seate…
- A hospital in Nagpur has 10 doctors. A panel of 4 doctors is to be formed. In how many ways can the panel be formed if a particular senior d…
- In how many different ways can 7 friends be seated around a circular table if only the relative positions of the friends matter (rotations a…
- A club in Kochi has 10 members. In how many ways can a team of 4 be chosen so that a particular member, Anil, is always included?
- What is the value of 12C4 + 12C5?