Glencoe Math: Course 3, Volume 2
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Glencoe Math: Course 3, Volume 2 View details
3. Volume of Spheres
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Exercise 7 Page 609

The volume of a sphere is four thirds the product of π and the cube of the radius.

about 107.2 seconds

Practice makes perfect

We are given that a spherical ball has a diameter of 8 inches.

We are asked to find how long it would take the ball to deflate. Let's start by calculating the volume of the ball. To do so, recall that the volume of a sphere is equal to four thirds the product of π and the cube of the radius r. V=4/3π r^3In this case, we are given the diameter of the sphere. To find the radius, we can divide the diameter d by 2.

r = d/2
r = 8/2
r = 4

We got that the radius of the sphere is 4 inches. Now we can substitute the radius into the formula and calculate the volume of the sphere.

V=4/3Ï€ r^3
V=4/3 π ( 4)^3
â–¼
Simplify right-hand side
V=4/3Ï€(64)
V=4Ï€(64)/3
V=268.082...
V≈ 268.1

Therefore, the volume of the ball is about 268.1 cubic inches. We also know that the ball has a slow leak in which the air escapes at the rate of 2.5 cubic inches per second. This means that we can use a proportion to find how long it would take the ball to deflate. Let's write the proportion! &2.5in^3/1sec=268.1in^3/xsec Now that the proportion is written, we will solve it using cross products and then isolating x.

2.5/1=268.1/x
2.5x=1(268.1)
â–¼
Solve for x
2.5x=268.1
2.5x/2.5=268.1/2.5
2.5x/2.5=268.1/2.5
x=268.1/2.5
x=107.24
x≈ 107.2

We got that it will take the ball about 107.2 seconds to deflate.