A capacitor is constructed using two concentric spheres and air as the dielectric medium (permittivity of air = \(8.854 \times 10^{-12} \, \text{F/m}\)). The radii of the inner and outer spheres are \(a = 10 \, \text{cm}\) and \(b = 15 \, \text{cm}\), respectively. The capacitance (in picofarads) is _________ (round off to 2 decimal places).