A vertical parallel-plate capacitor is half filled with a dielectric for which the dielectric constant is 2.00

Question:

A vertical parallel-plate capacitor is half filled with a dielectric for which the dielectric constant is 2.00 (Fig. P26.70a). When this capacitor is positioned horizontally, what fraction of it should be filled with the same dielectric (Fig P26.70b) in order for the two capacitors to have equal capacitance?

(a) (b)