AP EAMCET · Maths · Permutation Combination
If \({ }^n P_4=1680\), then \(n=\)
- A 6
- B 12
- C 10
- D 8
Answer & Solution
Correct Answer
(D) 8
Step-by-step Solution
Detailed explanation
\(\begin{aligned} & \text {Since, }{ }^n P_4=1680 \\ & \Rightarrow \quad n(n-1)(n-2)(n-3)=1680 \\ & \Rightarrow \quad n(n-1)(n-2)(n-3)=8 \times 7 \times 6 \times 5 \Rightarrow n=8 \end{aligned}\) Hence, option (d) is correct.
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