A Si single crystal with a length of $1\mathrm{.}5$m is grown by the Czochralski technique for the production of wafers with a desired boron dopant level of $1$ ppm$.$ Thus, $1$ ppm B is added to the Si melt. Calculate the boron concentration profile in the single crystal assuming that boron is incorporated into the single crystal according to the equilibrium partition coefficient of $0\mathrm{.}8.$ What portion of the single crystal would meet the specification that the dopant level is within $\backslash$pm $10\%$ of the target level.