<span>d. scientific theories summarize patterns found in nature
Hope this helps!</span>
For a cylinder that has both ends open resonant frequency is given by the following formula:

Where n is the resonance node, v is the speed of sound in air and L is the length of a cylinder.
The fundamental frequency is simply the lowest resonant frequency.
We find it by plugging in n=1:

To find what harmonic has to be excited so that it resonates at f>20Hz we simply plug in f=20 Hz and find our n:

We can see that any resonant frequency is simply a multiple of a base frequency.
Let us find which harmonic resonates with the frequency 20 Hz:

Since n has to be an integer, final answer would be 323.
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Answer:
f=1.92 cm
If ans is correct reply for explanation.
Answer:
The Production Function is the relationship between the quantity or variables of output and the different inputs quantities used in the production process.
Explanation:
Generally in quality, production or any business, we need to know what is the output with respect to different input variables. Suppose if an output is about bottle produce per hour, then we look at the inputs such as temperature, raw material/inventory, power supply, manpower, etc which are needed to produce bottle. any changes, for example in temperature could change the production rate.
Furthermore, a graph is made to see the production function.