ANSWER:
122 gallons
Explanation:
We have the following function:
![V=55\cdot\: cos\mleft((2\pi)/(7)t\mright)+67](https://img.qammunity.org/2023/formulas/mathematics/college/x2ipbpzas8uyyftu574ed2y4i2do4zvln0.png)
The first thing is to calculate the periodicity of the function. The value of the periodicity would be the value of x (in this case t) to calculate the value of y, that is, in this case the volume.
As follows:
![\begin{gathered} p=(2\pi)/((2\pi)/(7))=7 \\ \text{therefore x = 7, replacing} \\ V=55\cdot\: cos((2\pi)/(7)\cdot7)+67 \\ V=55\cdot\: cos(2\pi)+67 \\ V=55+67 \\ V=122 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/66hvvmuz08xypq406cnsbqhgwminxaomyv.png)
Therefore the maximum volume would be 122 gallons.