For a constructio project $,10$ ft of compacted earth fill is placed in preparation for erecting a building. At on of the building's interior locations, a machine foundation $20$ ft square will be installed weighing $2000$ kips. What net stress increase results below the center of the machine in the original soil mass, $5$ ft under the natrural ground surface? Assume a unit weight of $125$ pcf for the compacted fill. Assume the Boussinesq conditions apply.