So, the surface area of a sphere is
[tex]A\text{ = 4}\pi r^2[/tex]so, you have the value of A, and the value of pi, now you want to resolve for r
[tex]615.752\operatorname{mm}^2\text{ = }4\pi r^2[/tex][tex]\sqrt[]{(\frac{615.752\operatorname{mm}}{4\cdot\pi})}\text{ = r}[/tex]Then, r = 6.9999999mm... and the ask you to approximate to a whole number
the answer is r = 7mm
