1. The problem statement, all variables and given/known data A 490 pF capacitor consists of two 19 cm -radius circular plates, insulated with polystyrene Find the thickness of the polystyrene. 2. Relevant equations d = (ε_0 * Area * K) / C 3. The attempt at a solution I converted 490 pF to F 4.90 * 10^-10 F I converted 19 cm to meters .19 m and found the area of the plate ∏r^2 = ∏(.19)^2 = .1134 m^2 K of polystyrene = 2.3, so now just plug everything into my equation d = ((2.3) * (8.854*10^-12) * (.1134)) / (4.9 * 10^-10) d = .00471 m I want my answer in mm with two significant figures d = 4.7 mm mastering physics tells me this is the wrong answer, where did I go wrong?