Answer:
Option C is the answer.
Step-by-step explanation:
A ball is painted ruby red and costs $100.00 to paint and Ruby red paint costs $0.50 per square inch.
This means for an area of [tex]4\pi r^{2}[/tex], $100 were used. [tex]4\pi r^{2}[/tex] because the ball is a sphere.
where r is the radius.
We know that , Area of ball * cost of paint per square inch = total cost of paint.
[tex]4\pi r^{2} \times0.5=100[/tex]
[tex]2\pi r^{2}=100[/tex]
[tex]r^{2}= \frac{100}{2\pi }[/tex]
[tex]r^{2}=15.923[/tex] ; [tex]r=3.99[/tex] inch
Radius is 3.99 inches. or we can round this to 4 inches.
Hence, the diameter will be = [tex]2\times4=8[/tex] inches.
Therefore, option C: 8 inches is the answer.
