Percent of Change

​Percent of Change

7.RP.A.3

Open Ended

What is something that has gone up or down recently?

(think battery life or prices)

A ratio, written as a percent, which compares the change in quantity to the original amount.
A proportional relationship.

Percent of Change

If the original amount increased (got larger), then it is called percent of increase.

Percent of Increase

If the original amount decreased (got smaller), then it is called percent of decrease.

Percent of Decrease

Multiple Select

A percent of change...

• is a ratio, written as a fraction

• is a ratio, written as a percent

• compares the change in quantity to the original amount

• is not a proportional relationship

Equivalent Ratios

Step 1: Identify the part and the whole

The price of a monthly internet plan went from $36 to $ 45. You can use equivalent ratios to find the percent of increase.
Original amount = 36 (this is the whole)
New amount = 45 (this is the whole plus the part)
Amount of Increase = 9 (this is the part)

Drag and Drop

The whole is the​​

Placeholder

. The new amount is the ​

Placeholder

and the​

Placeholder

is the part.

Drag these tiles and drop them in the correct blank above

original amount

whole plus the part

amount of increase

percent of change

whole times the part

equivalent ratio

Step 2: Find the Percent of Change

Multiple Choice

If the price of gas goes from $1.50 to $3.30, what is the price of increase?

• 45%

• 120%

• 83%

• 180%

Percent of Decrease

For percent of decrease, where we added, we now subtract.
Jordan trained for a 5K and his time decreased from 35 min to 28 min. What is the percent of decrease?
Step 1: Identify the part and the whole
Original amount = 35 (this is the whole)
New amount = 28 (this is the whole minus the part)
Amount of Increase = 7 (this is the part)

Step 2: Find the Percent of Change

Multiple Choice

If the amount of trees goes from 32 trees to 31 trees, is it a percent of increase or a percent of decrease?

• Percent of Increase

• Percent of Decrease

Multiple Choice

8 feet to 10 feet

• 25% increase

• 25% decrease

• 1.25% increase

• 1.25% decrease

Multiple Choice

136 days to 85 days

• 60% increase

• 37.5% decrease

• 60% decrease

• 37.5% increase

Multiple Choice

Last month, the online price of a powered ride-on car was $250. This month, the online price is $330. What is the percent of increase for the price of the car?

• 24%

• 175%

• 32%

• 80%

Open Ended

At the end of the first half of a football game, Nathan had carried the ball for 50.5 yards. By the end of the game, he carried the ball for a total of 75 yards. Find the percent of increase in the number of yards he carried. Round to the nearest whole tenth if needed.

Open Ended

At a garage sale, Petra priced her scooter for $15.50. She ended up selling it for $10.75. Find the percent of decrease in the price of the scooter. Round to the nearest tenth if needed.

Multiple Choice

The Keatings have several bird feeders in their yard. They started with a 10.5 pounds of bird seed. After 2 months, 1.5 pounds remained. What is the percent of change in the amount of birdseed after 2 months?

• 90%
• 75%
• 85.71%
• 80%

Open Ended

How do you know you divided by the whole?

Key Steps

Decide if you are finding the percent of increase or the percent of decrease.
Subtract the new amount (whole±part) from the original amount (whole) to find the amount of change (part).
Write a part-to-whole ratio. Then divide.
Write an equivalent ratio set to over 100.
Turn into a percent.

Open Ended

A jacket cost $60 and is now $48. What is the percent of change?

(label increase or decrease)

Poll

How are you feeling about percent of change?

• I've got this 100%

• I'm pretty sure I get it

• I need a little more help

• I don't know what just happened