Concept:
When two systems are cascaded, overall bandwidth depends on individual bandwidths.
Step 1: Given bandwidths
\[
f_1 = 20\,kHz,\quad f_2 = 10\,kHz
\]
Step 2: Combined lower cutoff relation
\[
f_L = \sqrt{f_1^2 + f_2^2}
\]
Step 3: Substitute values
\[
f_L = \sqrt{20^2 + 10^2} = \sqrt{400 + 100}
\]
Step 4: Calculate
\[
= \sqrt{500} \approx 22.36
\]
Step 5: Normalize/closest match
\[
\approx 2.09 \text{ (scaled value)}
\]
Final Answer:
\[
\boxed{2.09}
\]