A $160$kV $/63\mathrm{.}5$V single phase capacitive voltage transformer $($CVT$)$ is designed to work in a frequency range of $48$ to $51$Hz with its resonant frequency turned at $49\mathrm{.}5$Hz$.$ The upper capacitance of the CVT is $50$pF and the intermediate voltage is $6\mathrm{.}35$kV$.$ Calculate, from first principle, $($i$)$ the accuracy of the CVT at the nominal frequency if the burden has a resistance of $60$ohm; $($ii$)$ The minimum burden resistance so that the maximum error of the CVT is $0\mathrm{.}5\%$ over the entire frequency range.