A) 10
B) 15
C) 9
D) 5
Correct Answer: C
Solution :
Given, \[^{n}{{P}_{4}}=24\,.{{\,}^{n}}{{C}_{5}}.\] Therefore,\[n(n-1)\,(n-2)\,(n-3)\] \[=24\times \frac{n(n-1)\,(n-2)\,(n-3)\,(n-4)}{5.4.3.2.1}\] \[\Rightarrow \]\[1=\frac{(n-4)}{5}\] Þ \[n-4=5\] Þ \[n=9\].You need to login to perform this action.
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