The frequency of the musical note C4 is about 261.63 Hz. What is the frequency of the note a perfect fifth below C4?

A- 130.82 Hz

B- 174.42 Hz

C- 256.63 Hz

D- 392.44

The frequency of the note a perfect fifth below C4 is;

B- 174.42 Hz

Step-by-step explanation:

Here we note that to get the "perfect fifth" of a musical note  we have to play a not that is either 1.5 above or 1.5 below the note to which we reference. Therefore to get the frequency of the note a perfect fifth below C4 which is about 261.63 Hz, we have

1.5 × Frequency of note Y = Frequency of C4

1.5 × Y = 261.63

Therefore, Y = 261.63/1.5 = 174.42 Hz.

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so: