First, we need to find the circular area. Since the radius is 5 feet, the circular area is given by
![\begin{gathered} A_c=\pi r^2 \\ A_c=3.1416(5^2) \\ A_c=78.54ft^2 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/obyd3h7ilxylbzv1vnyjqx15q3znqdlfhv.png)
We know that 1 bag covers 5x3=15 square feet, then the ratio Circular area to bags is
![\text{ratio}=\frac{circular\text{ area}}{\text{bag}}=(78.54)/(15)=5.236](https://img.qammunity.org/2023/formulas/mathematics/college/7drdzfe1ndqku8ziw3wz4h4cumac4ucwl6.png)
Therefore, by rounding up to the next integer, the answer is 6 bags.