Electrostatic Potential and Capacitance Part 2

A capacitor has air as dielectric medium and two conducting plates of area 12cm2 and they are 0.6‌cm apart. When a slab of dielectric having area 12cm2 and 0.6‌cm thickness is inserted between the plates, one of the conducting plates has to be moved by 0.2‌cm to keep the capacitance same as in previous case. The dielectric constant of the slab is : (Given E0=8.834×10−12F∕m)