Question

Janelle is painting a spherical model of a human cell for a science fair. She uses 615.44 square inches of paint to evenly cover the outside of the cell with one coat of paint. What is the diameter of the cell model? (Use 3.14 for the value of π.)

7 in.
8 in.
14 in.
16 in.

Answer 1

The diameter of the cell model is 7 inches.

janelle is painting a spherical model of human cell. This model is sphere in shape. So the paint needed to cover it's curved surface will be the whole surface area of that sphere.

we all know that the whole surface area formula = 4 π r²

here r is the diameter

So, 4 π r²=615.44

r²=615.44/4 π

r²= 49

r= √49

r=7

Answer 2

The surface area of a sphere is given by the formula:

Surface Area = 4πr^2

where r is the radius of the sphere.

We know that Janelle used 615.44 square inches of paint to cover the surface of the sphere, so we can set up the equation:

4πr^2 = 615.44

Divide both sides by 4π:

r^2 = 615.44 / (4π)

r^2 = 49.25

Take the square root of both sides:

r = 7

So the radius of the sphere is 7 inches. The diameter of the sphere is twice the radius, so the diameter is:

Diameter = 2r = 2(7) = 14

Therefore, the diameter of the cell model is 14 inches. Answer: 14 in.