Download Three-Types-of-Percent-Problems-ppt-2015

Three Types of Percent
Problems
Remember, percents are "parts of a whole".
The part is the numerator and the whole is the
denominator.
17% means 17 parts per 100 or
We are going to solve problems involving percents.
There are 3 types of problems:
1. Find the part What number is 54% of 34?
2. Find the whole 4 is 60% of what number?
3. Find the percent 18 is what percent of 28?
Two words that will occur in these types of problems
are "is" and "of".
These words have specific meanings in math.
"Is" means equals (=)
"Of" means multiply
To solve a percent problem, translate the words into an
equation.
Change the following:
1. Percent into a decimal
2. "is" to "="
3. "of" to " . "
4. Unknown to "x"
Then, solve the equation.
Finding the Part...
Examples:
Find
Write a mathematical sentence
40% of 60
.40
60 = 24
Click
20% of 90
.20
90 =Click
18
Write a mathematical sentence
What is 10% of 88?
Write a mathematical
sentence
X = .10
88
X = 8.8
Try these:
Find 12% of 70
What is 40% of 28?
Another Method:
You can also solve percent problems by setting up a
proportion.
Since percents are parts of a whole, you can create the
following proportion:
When figuring out which is the "part" and which is the
"whole", remember that you take a percent of the whole
and the answer is the part. In other words, the whole is
with the word "of" and the part is with the word "is".
Proportion Method
Steps
1. Set up the proportion as shown. is
of
=
%
100
Note: You can use this box to solve many problems
involving percents!
2. Substitute given values into the proportion.
Note: Try to find the numbers that are attached to the
words/symbols: is, of, or percent.
3. Solve the proportion.
Example: What is 25% of 400?
is
Steps
1. Set up the proportion.
of
2. Substitute.
What is 25% of 400?
3. Solve.
400 x 25 = 100w
10,000 = 100w
10,000/100 = w
100 = w
Click
?
400
=
25
%
100
100
Click on each box to see if
you substituted correctly.
Try it: What is 20% of 180?
is
Steps
1. Set up the proportion.
of
2. Substitute.
3. Solve.
=
%
100
Finding the Whole...
Remember, you can solve this by:
1. Translating into an equation
2. Setting up a proportion
40% of what number is 50?
.40
X = 50
X = 50
.40
X = 125
Try This:
100 is 20% of what number?
100 = .20
100 = x
.20
x = 500
x
Finding the Percent...
Remember, you can solve this by:
1. Translating into an equation
2. Setting up a proportion
What percent of 80 is 24?
x 80 = 24
X = 24
80
X = .30
X = 30%
60 is what percent of 15?
60 = X 15
60 = X
15
4=X
400% = X
You have just studied three different types of percent
problems.
Try all 3 types:
24 is 40% of what number?
42 is what percent of 840?
What is 30% of 45?