Solution:
(i) the $8^{\text {th }}$ term of the G.P., $0.3,0.06,0.012, \ldots$
It is known that,
$\mathrm{t}_{1}=\mathrm{a}=0.3, \mathrm{r}=\mathrm{t}_{2} / \mathrm{t}_{1}=0.06 / 0.3=0.2$
Using the formula.
$\begin{array}{l}
\mathrm{T}_{\mathrm{n}}=\mathrm{ar}^{\mathrm{n}-1} \\
\mathrm{~T}_{8}=0.3(0.2)^{8-1} \\
=0.3(0.2)^{7}
\end{array}$
(ii) the $12^{\text {th }}$ term of the G.P. $1 / a^{3} x^{3}, a x, a^{5} x^{5}, \ldots$
It is known that,
$t_{1}=a=1 / a^{3} x^{3}, r=t_{2} / t_{1}=a x /\left(1 / a^{3} x^{3}\right)=a x\left(a^{3} x^{3}\right)=a^{4} x^{4}$
Using the formula,
$\begin{array}{l}
T_{n}=a r^{n-1} \\
T_{12}=1 / a^{3} x^{3}\left(a^{4} x^{4}\right)^{12-1} \\
=1 / a^{3} x^{3}\left(a^{4} x^{4}\right)^{11} \\
=(a x)^{41}
\end{array}$