Boron occurs in two varieties, namely ${ }^{10}\mathrm{B}$ ( atomic mass: $10.01 \mathrm{amu}$) and ${ }^{11}\mathrm{B}$ ( atomic mass: $11.01 \mathrm{amu}$ ). The atomic mass of naturally occurring element is reported as $10.82 \mathrm{amu}.$ The percent of ${ }^{10}\mathrm{B}$ is 6this naturally occurring boron is