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6-8 Accelerated 7 Unit 3 Lesson 11

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Unit 3, Lesson 11

Solving Problems about Percent Increase or Decrease

Accelerated 7

Practice

Problem 1

Select all expressions that show \(x\) increased by 35%.

\(1.35x\)
\(\frac{35}{100}x\)
\(x + \frac{35}{100}x\)
\(( 1+0.35)x\)
\(\frac{100+35}{100}x\)
\((100 + 35)x\)

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Lesson 11 Resources

Student Materials

Problem 2

Here are two stories:

The initial freshman class at a college is 10% smaller than last year’s class. But then during the first week of classes, 20 more students enroll in the class. There are then 830 students in the freshman class.
A store reduces the price of a computer by \$20. Then during a 10% off sale, a customer pays \$830 for the computer.

Here are two equations:

\(0.9x+20=830\)
\(0.9(x-20)=830\)

Decide which equation represents each story.
Explain why one equation has parentheses and the other doesn’t.
Solve each equation, and explain what the solution means in the situation.

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Problem 3

ForLesson 10: Using Equations to Solve Problems

A marimba (muh-RIM-bah) is a musical instrument that came from Africa and is used throughout Central America. A marimba has wooden bars of different lengths. It is played by striking the bars with a mallet.

On one marimba, the longest bar measures \(15\frac38\) inches long. Each bar after that is \(\frac38\) inch shorter than the bar before it. The shortest bar on the marimba is \(7\frac12\) inches long. Write and solve an equation to find the number of bars on this marimba.

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Problem 4

ForLesson 2: Scale Factors and Making Scaled Copies

Here is an unlabeled polygon, along with its scaled copies Polygons A–D. For each copy, determine the scale factor. Explain how you know.

An unlabeled four sided polygon with four different scale copies labeled A, B, C and D on a square grid.

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