Final answer:
The frequency of the note a perfect fifth below C4, which is F3, is calculated by multiplying the frequency of C4 (261.63 Hz) by 2/3, resulting in 174.42 Hz.
Step-by-step explanation:
The frequency of the musical note C4 is about 261.63 Hz. A perfect fifth below a note is 7 half-steps below on the chromatic scale, which corresponds to a frequency ratio of approximately 2/3. Therefore, to find the frequency of the note that is a perfect fifth below C4, we multiply the frequency of C4 by 2/3.
Calculating this, 261.63 Hz × (2/3) = 174.42 Hz which is the note F3. Hence, the frequency of the note a perfect fifth below C4 is 174.42 Hz.