Answers

2014-05-28T01:10:31+05:30
(n-1)P3 / nP4 = 1/9
{(n-1)! / (n-1-3)!} / {n! / (n-4)!} = 1/9
(n-1)! / n! = 1/9                    (n! = 1*2*3*4................*(n-1)*n)
1/n = 1/9
n = 9
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