A) 10
B) 11
C) 12
D) 9
E) 8
Correct Answer: C
Solution :
\[^{n}{{C}_{3}}=220\] \[\Rightarrow \] \[\frac{n!}{(n-3)!3!}=220\] \[\Rightarrow \] \[n(n-1)(n-2)=220\times 6\] \[\Rightarrow \] \[n(n-1)(n-2)=12(12-1)(12-2)\] \[\Rightarrow \] \[n=12\]You need to login to perform this action.
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