The roots of polynomial $ p(b) $ are:
$$ \begin{aligned}b_1 &= 3.5593\\[1 em]b_2 &= 1.0934+2.7969i\\[1 em]b_3 &= 1.0934-2.7969i\\[1 em]b_4 &= -2.873+1.7208i\\[1 em]b_5 &= -2.873-1.7208i \end{aligned} $$Polynomial $ b^5-5b^3+4b-360 $ has no rational roots that can be found using Rational Root Test, so the roots were found using Newton method.