A prospector finds a solid rock composed of granite (\rho = 2560 {\rm kg/m^{3}}) and gold. The volume of the rock is 3.45×10?4{\rm m^{3}} , and its mass is 4.01{\rm kg} . Part A What mass of gold is contained in the rock? m_{\rm gold} = {\rm kg} What percentage of the rock is gold by volume?