A) 3
B) 4
C) 5
D) 6
Correct Answer: C
Solution :
\[^{n+1}{{C}_{3}}=2\,.{{\,}^{n}}{{C}_{2}}\] Þ \[\frac{(n+1)!}{3!\,.\,(n-2)!}=2\,.\,\frac{n!}{2!.(n-2)!}\] Þ \[\frac{n+1}{3\,.\,2!}=\frac{2}{2!}\] Þ \[n+1=6\,\,\Rightarrow \,n=5\].
You need to login to perform this action.
You will be redirected in
3 sec
