# Math Help - percentile help with CDF

1. ## percentile help with CDF

I need to understand part b.

how did they get n(p)

in other words, how did they go from
p = F(n(p)) ......to n(p)

see the attachment!

2. That's just the quadractic equation. Let x be the $p^{th}$ percentile

so p=F(x) or $p=2(x+{1\over x} -2)$

multiply by x and create a quad equation

$px=2(x^2+1 -2x)$

$x^2 -(2+{p\over 2})x+1=0$