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Big Ideas Math: Modeling Real Life, Grade 8

BI

Big Ideas Math: Modeling Real Life, Grade 8 View details

1. Volumes of Cylinders

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Exercise 6 Page 429

Use the formula for the volume of a cylinder.

12.0 feet

Practice makes perfect

We are given the following cylinder and we want to find the value of its volume.

The volume of a cylinder with the radius r and height h can be calculated by the following formula. V=π r^2 h Since we are given the volume and radius of the cylinder, we can substitute them into the formula and calculate its height.

V=π r^2 h

V= 340, r= 3

340=π ( 3)^2h

▼

Solve for h

Calculate power

340=π(9)h

CommutativePropMult

Commutative Property of Multiplication

340=9π h

π= 3.141592...

340=9( 3.141592...) h

Multiply

340=(28.274333... )h

.LHS /28.274333... .=.RHS /28.274333... .

340/28.274333...=(28.274333...)h/28.274333...

CancelCommonFac

Cancel out common factors

340/28.274333...=(28.274333...)h/28.274333...

Simplify quotient

340/28.274333...=h

Calculate quotient

12.025040...=h

Rearrange equation

h=12.025040...

Round to 1 decimal place(s)

h=12.0

Therefore, the height of the cylinder is about 12.0 feet.

Subchapter links

Try It p.428-429

Self-Assessment for Concepts & Skills p.429

Self-Assessment for Problem Solving p.430

Review & Refresh p.431

Concepts, Skills, & Problem Solving p.431-432