A capacitor is made from two concentric spheres, one with radius $5\mathrm{.}10$ cm $,$ the other with radius $8\mathrm{.}40$ cm $.$

$($a$)$ What is the capacitance of this set of conductors $($in pF $)?$

$$ pF

$($b$)$ If the region between the conductors is filled with a material whose dielectric constant is $5\mathrm{.}60,$ what is the capacitance of the system $($in pF$)?$

$$ pF