In the given diagram, a 6 km high plateau is supported by a crustal root of thickness \(r\). The system is in isostatic equilibrium as per Airy’s hypothesis of isostasy. Densities of the crust and the mantle are 2800 kg/m\(^3\) and 3100 kg/m\(^3\), respectively. Assuming the acceleration due to gravity to be same throughout the region, the thickness of the root (\(r\)) is _________ km.
