Answer :
Answer:
r = 6.69 inches
Step-by-step explanation:
We have,
Marcus is building a model of Earth using a sphere with a surface area of [tex]400\pi\ \text{inch}^2[/tex].
It is required to find the radius of the sphere Marcus is using for his model.
The surface area of a circular shaped object is given by :
[tex]A=\dfrac{4}{3}\pi r^3[/tex]
r is radius
[tex]r=(\dfrac{3A}{4\pi})^{1/3}\\\\r=(\dfrac{3\times 400\pi}{4\pi})^{1/3}\\\\r=6.69\ \text{inch}[/tex]
So, the radius of the sphere is 6.69 inches.