Question

Thirty beats are heard in one minute when two notes are played together. If the higher note has a frequency of 740 Hz, what is the frequency of the lower note?1) 742 Hz2) 738 Hz3) 739.5 Hz4) 740.5 Hz

Answer 1

`3)739.5Hz`

Step-by-step explanation

First, let us convert the frequency from beats per minute to beats per second (Hertz):

`\begin{gathered} 30\text{bpm}=(30)/(60)\text{beats per second} \\ \Rightarrow0.5\text{bps}=0.5Hz \end{gathered}`

To find the frequency of the lower note, we have to find the difference between the frequency of the higher note and the frequency calculated above.

That is:

`\begin{gathered} 740-0.5 \\ \Rightarrow739.5Hz \end{gathered}`

The answer is option 3.