Since, Intensity ∝ width of slit (ω) $\begin{aligned}
& \text { so, } I_1=I, I_2=4 \mathrm{I} \
& I_{\min }=\left(\sqrt{I_1}-\sqrt{I_2}\right)^2=I \
& I_{\max }=\left(\sqrt{I_1}+\sqrt{I_2}\right)^2=9 \mathrm{I} \
& \frac{I_{\max }}{I_{\min }}=\frac{9 \mathrm{I}}{\mathrm{I}}=\frac{9}{1}
\end{aligned}$