Explanation

(a) Loudness, $L = 10\log_{10}\frac{I}{I_{0}}$
$60 = 10\log_{10}\frac{I_{1}}{I_{0}}$
$\Longrightarrow \frac{I_{1}}{I_{0}} = 10^{6}\ \ \ \ \ \ldots(i)$
$similarly,\ \ \ \ \ 30 = 10\ lig_{10}\frac{I_{2}}{I_{0}}$
$\frac{I_{2}}{I_{0}} = 10^{3}\ \ \ldots(ii)$
Dividing Eq. (i) by Eq. (ii), we get
$\frac{I_{1}}{I_{2}} = 1000$