Find the volume of the tank:
![V=\pi\cdot r^2\cdot h](https://img.qammunity.org/2023/formulas/mathematics/college/n3115jxdztqydpk839rmiw7mlgufr9g5b6.png)
The radius of a circle is equal to the half of its diameter:
![\begin{gathered} d=50ft \\ \\ r=(50ft)/(2)=25ft \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/bjsqpu1xl7lwglvgkdiclp0ye73xsfww0u.png)
Then, the volume of the tank is:
![\begin{gathered} V=\pi\cdot(25ft)^2\cdot2.5ft \\ \\ V=4908.73ft^3 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/kynzk9vshsy9vpnt99vuo1hjnz3q5m562f.png)
1 cubic foot = 7.48 gallons
1 gallon of chlorine = 3000 galons of water
![4908.73ft^2water\cdot\frac{7.48\text{gal water}}{1ft^2\text{ water}}\cdot\frac{1\text{ gal chlorine}}{3000\text{ gal water}}=12.24gal\text{ chlorine}](https://img.qammunity.org/2023/formulas/mathematics/college/bm6lvmsro0j384dk3iqjnn7br0x8happ27.png)
It is necesary to buy 13 gallons of chlorine as it is necesary to use 12.24 gallons to clean the tank