4. A crystal boule of silicon is to be grown by the Czochralski method. Boron is added to the melt in the form of heavily Boron doped polySi, producing an initial melt concentration, C0=1017cm3. If the total weight of silicon to be melted is 10kg, how many kg of pure EGS, and how many kg of Boron doped polysilicon, at concentration NA=1019cm3, are needed ? Assume that the density of doped and undoped Si are the same