Explanation

(b) $\frac{I_{\max}}{I_{\min}} = \frac{4}{1}\ \frac{\left( a_{1} + a_{2} \right)^{2}}{\left( a_{1} - a_{2} \right)^{2}}$
$Or\ \ \ \ \ \ \ \ \ \ \ \frac{a_{1} + a_{2}}{a_{1} - a_{2}} = \frac{2}{1}$
Or ${\ \ \ \ \ \ \ \ a}_{1} + a_{2} = 2a_{1} - 2a_{2}$
Or $a_{1} = 3a_{2}$
$\therefore\ \ \ \frac{I_{1}}{I_{2}} = \frac{a_{1}^{2}}{a_{2}^{2}} = \frac{\left( 3a_{2} \right)^{2}}{a_{2}^{2}} = \frac{9}{1}$
$\therefore\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \frac{a_{1}}{a_{2}} = \frac{3}{1}$