Transcript Percent of Change with Equations (Day 3)

Percent of Change with Equations
(Day 3)
Friday, April 8, 2016
We are learning to…find percents and parts of change
using the equation (percent as a decimal)(total) = part.
Warm Up
 With your team use your proportional reasoning
skills to find the following solutions.
 Raise your hand when you are done with these
two warm up questions.
Parts of Change with Equations
 Today we are going to use equations to find parts of change.
 Today the questions will have the phrases:
 #% more than…
 #% less than…
 Remember that we will need to first solve for the parts.
 Then add or subtract this part from the original total to find the
solution.
What number is 65% more than 800?
The total is…
Increasing
Identify values and
define variables
Decreasing
x
Part =___________
65
….by _________%
800
Total =___________
0.65(800) = x
Equation: ________________________________
Solution Process:
0.65(800) = x
520= x
0.65
Percent =__________
(as a decimal)
So we first need to
find…
65% of 800
_________________
Amount Increased or
Decreased:
Add or subtract from
the original total:
Solution as a sentence:
65% more than 800 is 1,320.
520
800 + 520 =
1,320
What number is 3.5% less than 300?
The total is…
Increasing
Identify values and
define variables
Decreasing
x
Part =___________
3.5
….by _________%
300
Total =___________
0.035(300) = x
Equation: ________________________________
Solution Process:
0.035(300) = x
10.5 = x
0.035
Percent =__________
(as a decimal)
So we first need to
find…
3.5% of 300
_________________
Amount Increased or
Decreased:
Add or subtract from
the original total:
Solution as a sentence:
3.5% less than 300 is 289.5.
10.5
300 - 10.5 =
289.5
Try some practice with your team!
Percent of Change with Equations
 Today let’s try to shorten the process when finding new totals after
a percent of change.
 First think about this situation:
 What number is 20% more than 60?
Let’s say that 60 is 100% …and we need another 20%
So we have 100% + 20% …or a 120% of the original 60.
Just find 120% of 60 and you’ll have your solution!
percent as a decimal (total) = part
1.2 (60) = 72
Percent of Change with Equations
 Think about this situation:
 What number is 65% less than 80?
Let’s say that 80 is 100%
Think of it as money…if
you had a 65% discount
you would only be
paying 35% of the
original cost!
…and we need to take away 65%
So we have 100% - 65% …or a 35% of the original 80.
Just find 35% of 80 and you’ll have your solution!
percent as a decimal (total) = part
0.35 (80) = 28
Try some practice with your team!