$6^{\mathrm{t}\mathrm{h}}$ Person asked is the $2^{\mathrm{n}\mathrm{d}}$ person to know the answer

$\Rightarrow$In the first five people there must be exactly one person who knows the answer
Required probability $=\frac{{\mathrm{}}^9{\mathrm{C}}_4{\times }^3{\mathrm{C}}_1}{{\mathrm{}}^{12}{\mathrm{C}}_5}\times \frac{2}{7}$
$=\frac{9\times 8\times 7\times 6\times 120\times 3}{24\times 12\times 11\times 10\times 9\times 8}\times \frac{2}{7}=\frac{3}{22}$