Notes – Percents of Change (Day 4)

Thursday, April 20, 2023

We are learning to… solve for parts, totals, and percents using proportional reasoning.

Percents of Change

Today we will be looking for percents of change. We will be given two totals:

A total before the change. And a total after the change.

Our job is to:1. Find the change (or difference) between the two totals.

2. This change represents the missing part.

3. Then compare this part to the original total.

4. Solve for the missing percent which represents the change between the totals.

Finding a Percent of ChangeIn the first grading period 40 people received A’s in Mrs. Hauptman’s class. In

the second grading period 70 people received A’s. What is the percent of

increase from the first quarter to the second quarter?

The original total was:______ and then the amount changed to:_______.40 70

The amount of change:(Increase or Decrease)

3070 – 40 =

Find the percent of change from the original total:

100

x

30

40

(100) (100)

300

4x

75x

Solution as a sentence:

“75% more students had A’s

for the second quarter than the

first quarter.”

Table:(Remember to use the original total)

Parts Totals

30 40

x 100

3

100 4

x

This change represents the PART!

Finding a Percent of ChangeOn Monday 215 students bought lunch and on Tuesday only 172

student bought lunch. What is the percent of decrease of students who

bought lunch from Monday to Tuesday?

The original total was:______ and then the amount changed to:_______.215 172

The amount of change:(Increase or Decrease)

43215 – 172 =

Find the percent of change from the original total:

100

x

43

215(100) (100)

4300

215x

20x

Solution as a sentence:

“20% less students bought

lunch on Tuesday compared to

Monday.”

Table:(Remember to use the original total)

Parts Totals

43 215

x 100

This change represents the PART!

Independent Practice

Find the following percents of increase and decrease quietly and independently.

State your solution in form for a complete sentence relating back to the problem.

When you are finished quietly raise your hand to have your teacher check your solutions.

Group Practice The group who works best together today will have their

homework assignment cut in half…we’re looking for a group who can: Stay in the same place…no one rushes ahead or falls behind Help each other with the assignment Stay focused on math

Be sure to analyze each question carefully before attempting to find the solution. Underline or circle important words to help.