Three signal-frequency rows show low-pass output falling as the source moves above cutoff. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Zero hertz is fully inside a low-pass
With cutoff 6 hertz, a 0 hertz signal has low-pass ratio 1. Output budget stays 20.
20⋅1=20
At cutoff the low-pass keeps one half
The signal rises to 6 hertz, equal to cutoff. The exact squared ratio is 1/2, so output budget is 10.
20⋅21=10
Twelve hertz is above cutoff and mostly rejected
At 12 hertz against the same cutoff, the ratio is 1/5. Output budget falls to 4.