Question

Ruby red paint costs $0.50 per square inch. A ball is painted ruby red and costs $100.00 to paint. What is the diameter of the ball? Round to the nearest tenth of an inch.. A.4.0 in.. B.5.6 in.. C.8.0 in.. D.16.0 in.

Answer 1

The diameter can be obtained by the formula A = pi*r^2

First, multiply 0.50 * 100 to obtain the area of the ball, then simplify and solve for the radius. Doubling the radius would yield the diameter. This is shown below:

Area of the ball = 0.50 * 100 = 50 in^2
A = pi*r^2
50 = (3.14)*r^2
r = 3.99 = approx. 4
diameter = 2r
Diameter = 8 inches.

Among the choices, the correct answer is C. 8.0 in. 

Answer 2

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 $4\pi r^{2}$, $100 were used. $4\pi r^{2}$ 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.

$4\pi r^{2} \times0.5=100$

$2\pi r^{2}=100$

$r^{2}= \frac{100}{2\pi }$

$r^{2}=15.923$ ; $r=3.99$ inch

Radius is 3.99 inches. or we can round this to 4 inches.

Hence, the diameter will be = $2\times4=8$ inches.

Therefore, option C: 8 inches is the answer.