Answer:
The lower frequency is
![f_1 = 265.55 \ Hz](https://img.qammunity.org/2021/formulas/physics/college/rqwi69lc7yp62g7ogu7g3xtzdlucxltwj9.png)
The higher frequency is
![f_2 = 266.4546 \ Hz](https://img.qammunity.org/2021/formulas/physics/college/lcrwfb0580udzchhnnk4ty620km0282fk8.png)
Step-by-step explanation:
From the question we are told that
The period is
![T = 2.20 \ s](https://img.qammunity.org/2021/formulas/physics/college/n2bzj89q62176df5kdmtybb110r8lnaqx8.png)
The frequency of the tuning fork is
![f = 266.0 \ Hz](https://img.qammunity.org/2021/formulas/physics/college/w9j0uabp9ml4ji6kybrkg59royidv26vfb.png)
Generally the beat frequency is mathematically represented as
![f_b = (1)/(T)](https://img.qammunity.org/2021/formulas/physics/college/4xbmsyowmhqyybyltjbdibhar69uicgngk.png)
substituting values
![f_b = (1)/(2.20)](https://img.qammunity.org/2021/formulas/physics/college/5g4u7yzeh6057yqln07wus0rv0tw2z44yk.png)
![f_b = 0.4546 \ Hz](https://img.qammunity.org/2021/formulas/physics/college/upoj7xzathp2fskaltbuo332eorau6noqd.png)
Since the beat frequency is gotten from the beat produced by the tuning fork and and the string then
The possible frequency of the string ranges from
![f_1 = f- f _b](https://img.qammunity.org/2021/formulas/physics/college/y5ma332p2p8s9zatikk3td7olvwybli2u1.png)
to
![f_2 = f + f_b](https://img.qammunity.org/2021/formulas/physics/college/graowz44lw4ur2wv0yq1osw9re842917qw.png)
Now substituting values
![f_1 = 266.0 - 0.4546](https://img.qammunity.org/2021/formulas/physics/college/xvygbnj4thozxez105zvn60zuz7y7ga0zw.png)
![f_1 = 265.55 \ Hz](https://img.qammunity.org/2021/formulas/physics/college/rqwi69lc7yp62g7ogu7g3xtzdlucxltwj9.png)
For
![f_2](https://img.qammunity.org/2021/formulas/physics/college/p0sxmna6061wocbk9vo552zgc9w02kj4el.png)
![f_2 = 266 + 0.4546](https://img.qammunity.org/2021/formulas/physics/college/r6eifaujfakt73v8rk4eunqdk6va7cpmnx.png)
![f_2 = 266.4546 \ Hz](https://img.qammunity.org/2021/formulas/physics/college/lcrwfb0580udzchhnnk4ty620km0282fk8.png)