The formula for determining the frequency, [tex]f[/tex], of a note on a piano is [tex]f = 440 \cdot 2^{\frac{h}{12}}[/tex], where [tex]h[/tex] is the number of half-steps from the [tex]A[/tex] above middle [tex]C[/tex] on the keyboard.

A note is six half-steps away from the [tex]A[/tex] above middle [tex]C[/tex]. The frequency of the [tex]A[/tex] above middle [tex]C[/tex] is [tex]440 \, \text{Hz}[/tex].

How much greater is the frequency of the new note compared with the frequency of the [tex]A[/tex] above middle [tex]C[/tex]?

A. 29.3%
B. 41.4%
C. 70.7%
D. 182.3%



Answer :

To determine the frequency of the new note and its percentage increase relative to the frequency of the A above middle C, let's follow these steps:

1. Identify Known Values:
- Frequency of A above middle C ([tex]\( f_A \)[/tex]) = 440 Hz
- Number of half-steps away ([tex]\( h \)[/tex]) = 6

2. Determine Frequency of the New Note:
The formula for the frequency [tex]\( f \)[/tex] of a note that is [tex]\( h \)[/tex] half-steps away from A above middle C is:
[tex]\[ f = 440 \times 2^{\frac{h}{12}} \][/tex]
Plugging in [tex]\( h = 6 \)[/tex]:
[tex]\[ f = 440 \times 2^{\frac{6}{12}} \][/tex]
[tex]\[ f = 440 \times 2^{0.5} \][/tex]
[tex]\[ f = 440 \times \sqrt{2} \][/tex]
[tex]\[ f \approx 440 \times 1.41421356 \][/tex]
[tex]\[ f \approx 622.254 \, \text{Hz} \][/tex]

3. Calculate the Percentage Increase:
The percentage increase in frequency is given by:
[tex]\[ \text{Percentage Increase} = \left( \frac{\text{New Frequency} - \text{Original Frequency}}{\text{Original Frequency}} \right) \times 100 \][/tex]
Using the values we have:
[tex]\[ \text{Percentage Increase} = \left( \frac{622.254 - 440}{440} \right) \times 100 \][/tex]
[tex]\[ \text{Percentage Increase} = \left( \frac{182.254}{440} \right) \times 100 \][/tex]
[tex]\[ \text{Percentage Increase} \approx 0.41421356 \times 100 \][/tex]
[tex]\[ \text{Percentage Increase} \approx 41.421 \% \][/tex]

4. Find the Closest Choice:
Comparing the calculated percentage increase (41.421%) to the provided options:
- 29.3%
- 41.4%
- 70.7%
- 182.3%

The closest match to 41.421% is 41.4%.

So, the frequency of the new note is approximately 622.254 Hz, and the percentage increase in frequency compared to the A above middle C is approximately 41.4%.

Therefore, the correct answer is 41.4%.