Answer
$3.6\times10^5Hz$
Work Step by Step
Equation 21-19 gives the resonant frequency. It is not necessary to know the resistance of the inductor.
$$f_o=\frac{1}{2 \pi}\sqrt{\frac{1}{LC}}$$
$$f_o=\frac{1}{2 \pi}\sqrt{\frac{1}{(55.0\times10^{-6}H)(3500\times10^{-12}F)}}$$
$$ =3.6\times10^5Hz$$