If 5* nP3 = 4* (n+1)P3, find n?	Choose the correct choice from the following choices.
A) 10 B) 11 C) 12 D) 14 E) None
Solution:   nP3 = n*(n–1)*(n–2).   (n+1)P3 =(n+1)*n*(n–1).   Now,   5*n*(n–1)*(n–2) = 4* (n+1)*n*(n–1).   Or, 5(n−2) = 4(n+1).   Or, 5n−10 = 4n+4.   Or, 5n−4n = 4+10.   Hence, n = 14.   Note: nPr = [n! /(n -r)!].   Answer: Option 14
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If 5* nP3 = 4* (n+1)P3, find n?