If `P(n-1,\ 3): P(n ,4)=1:9` find n

Explanation

Given:
`P(n−1,3):P(n,4)=1:9`



=`(P(n−1,3))/(P(n,4))=1/9`​



=`((n−1)!​)/((n−1−3)!)xx((n−4)!)/(n!)=1/9`

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