Percent of Change

Reminders:
Be prepared and active
Be courteous and respectful
Stay in your seat unless given
permission
Voice Level 0 during warm-up
and the teacher's instruction
time, we cannot do two things
at the same time

​Tuesday
10/8/24

Poll

How are you feeling today?

• Happy

• Excited

• Motivated

• Energized

The table shows the cost for x pounds of bananas.  What is the cost for one pound of bananas?

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Warm-up

Fill in the Blanks

The graph models the speed of an amusement park ride. The coordinates of Point W are (1, r).  What is the meaning and value of r at Point W?

Warm-up

Multiple Choice

The graph models the speed of an amusement park ride.

The coordinates of Point W are (1, r).  What is the meaning and value of r at Point W?

• r represents the unit rate of speed of 1 meter per 45 seconds

• r represents the unit rate of speed of 45 meter per 1 second

• r represent the rate of increase of speed of 1 meter per 45 seconds

• r represents the rate of increase of speed of 45 meters per 1 second

Multiple Select

Let us recall our previous lesson.

Are the expressions the same or different?

Select all that applies.

• All have a value of 6

• A, C, and D are all written as percents

• B and D both result in a number less than the second factor.

• B is the only one that includes a decimal.

Explore

Learning Target

Use proportional relationships to solve
multistep ratio and percent problems.

SESSION 1

Percent Change

LESSON 21 • Solve Problems Involving Percent Change and Percent Error

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Solve and support your thinking

Before editing, a movie is 120 min long.
The edited movie is 25% shorter. What
is the length of the edited movie?

Math Toolkit double number lines, grid paper

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Before editing, a movie is 120 min long. The edited movie is 25% shorter. What is the length of the edited movie?

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​Make sense of the problem

Fill in the Blanks

Before editing, a movie is 120 min long. The edited movie is 25% shorter. What is the length of the edited movie?

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​Strategy A

Before editing, a movie is 120 min long. The edited movie is 25% shorter. What is the length of the edited movie?

​

​Strategy B

Before editing, a movie is 120 min long. The edited movie is 25% shorter. What is the length of the edited movie?

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​Strategy C

Percent Change
*Percent Increase
*Percent Decrease
Percent Error

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A percent change is a percent that compares the change in a quantity to the original quantity.

​Percent Change

When the new amount is greater than the original amount, the percent change is called a percent increase.

​Percent Increase

When the new amount is less than the original amount, the percent change is called a percent decrease

​Percent Decrease

Multiple Choice

Is a discount a percent increase or a percent decrease?

• Percent Increase

• Percent Decrease

Multiple Choice

James bought a jacket on sale for $45. The jacket originally cost $60. What was the percentage of discount?

• 15%

• 20%

• 25%

• 30%

Compares the amount of error to the correct amount. The amount of error is the positive difference between the correct amount and an incorrect amount.

​Percent Error

Multiple Choice

A store sells 10-lb bags of apples. One of the bags actually weighs 9.9 lb. What is the correct amount?

• 10 lbs

• 9.9 lbs

• 0.1 lbs

• 19.9 lbs

Multiple Choice

A store sells 10-lb bags of apples. One of the bags actually weighs 9.9 lb. What is the new amount?

• 9.9 lbs

• 10 lbs

• 19.9 lbs

• 0.1 lb

Multiple Choice

A store sells 10-lb bags of apples. One of the bags actually weighs 9.9 lb. What is the amount of error?

• 0.1

• 0.01

• 0.001

• 1

Multiple Choice

A store sells 10-lb bags of apples. One of the bags actually weighs 9.9 lb. What is the percent error?

• 1%

• 10%

• 0.1%

• 1.1%

Multiple Choice

Billy earns 6% commission on each car that he sells. If he sold a car for $14,000, how much commission did he earn? This type of problem is an example of ___________.

• commission

• markdown

• markup

• tip

Multiple Choice

Anders owns a hat shop. During a sale, he sells all his hats for 20% off. Is this a markup or markdown?

• Markup

• Markdown

How are a percent error and a percent change similar? How are they different?

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​Reflect:

Open Ended

How are a percent error and percent change similar?

How are they different?

always positive

​Percent Error

Can be a positive of a negative

​Percent Change

Percent Change and Percent Error

Both compare a different amount.

• Anonymous

" Life is a Math equation. In order to gain the most, you have to know how to convert negatives into positives. "