Introduction to Percents

Percent Like a fraction or a decimal,

represents part of a whole. Means hundredths or parts in 100 Symbol is %

25% = 25/100 = 0.25 (25 parts of 100 parts)

33% = 33/100 = 0.33 (33 parts of 100 parts)

Identify Terms Used With Percents

Drop percent symbol and divide by 100 35% = 35/100 = 0.35

Drop percent symbol and move decimal point 2 places to the left 35% = 35.0 = 0.35

Write A Percent As A Decimal

Convert the following percentages to decimals

Let’s Try It

1. 27% = 2. 54% =

3. 49% = 4. 85% =

5. 72% = 6. 12% =

7. 5% = 8. 22%

9. 67% = 10. 99%

To write a mixed number percent as a decimal Change the fractional part of the

mixed number to a decimal percent.

8 ¼% = 8.25%

Convert decimal percent to its decimal equivalent Move decimal point 2 places to the left

8.25% = 0.0825

Writing Mixed Number Percentages as Decimals

Convert the following fractional percentages to decimals Round numbers to the nearest hundredth

Let’s Try It

1. 9-1/4% = 2. 5-4/5% =

3. 5-3/4% = 4. 42-1/5% =

5. 7-2/5% = 6. 12-3/4% =

7. 63-2/4% =

8. 2-3/5%

9. 20-3/5% =

10. 9-4/5%

1/5 Convert the fraction to its decimal

equivalent1/5 = 0.20 1 ÷ 5

= .20

Convert the decimal to percent Move decimal point 2 places to the right

and add percent symbol

0.20 = 20%

Common Fractions as Percents

Fraction Decimal Percent

5/8 = 0.625 = 62.5%

3/6 = 0.5 = 50%

6/8 = 0.75 = 75%

Examples

To convert fractions to decimals • divide the numerator by the

denominator

Let’s Try ItFraction Decimal Percent

1/2 = =

1/3 = =

2/3 = =

¼ = =

¾ = =

1/5 = =

2/5 = =

3/5 = =

Let’s Try ItFraction Decimal Percent

4/5 = =

1/8 = =

3/8 = =

5/8 = =

1/10 = =

5/10 = =

7/10 = =

Complete Worksheet 3.1 #1 - 40

Independent Practice

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Part, Rate and Base

Percents are commonly used to determine interest, sales, taxes, commissions, and discounts or to make comparisons

Base Represents 100% That to which something is being

compared Rate

Number followed by percent symbol The percent one number is of another

one May be written as decimal of fraction

Part The number that is a portion of the base

Key Terms

As an Equation Part = Base x Rate

As a proportionIS

OF

%

100

=

What is a 30% discount on a $150 jacket?

Equation: Part = Base x Rate ? = $150 x 30%

For Example

$150 x .30 = $45Convert to decimal and multiply

What is a 30% discount on a $150 jacket?

Proportion

For Example

IS

OF

%

100

=X

150

30

100

=

Cross Multiply

100X = (30)(150)

100X = 4500

100X = 4500 100 100

Divide both sides by 100

X = $45

What is 6.5% of 130? Equation

Part = Base x Rate X = 130 x .065 X = 8.45

Parts with decimals

What is a 6.5% of 130?

Proportion

Parts With Decimals

IS

OF

%

100

=X

130

6.5

100

=

Cross Multiply

100X = (6.5)(130)

100X = 845

100X = 845 100 100

Divide both sides by 100

X = 8.45

Suppose you had a gain of 6-1/4% on $400. What was the gain?

Change fractional percent to a decimal percent6.25%

Drop percent symbol and move decimal point to the left two spaces

.0625

Apply formula: Part = Base x Rate X = $400 x .0625

X = $25

The gain was $25

Parts with Fractions

Rate = Part ÷Base

Finding Rate

What percent is $15 of $139?

Example:

X = 15 ÷ 139X = 0.108 = 10.8%

What percent is $15 of $139? Proportion

For Example

IS

OF

%

100

=15

139

X

100

=

Cross Multiply

1500 = 139X1500 = 139X 139 139

Divide both sides by 139

X = 10.8

Complete Worksheet 3.2A & 3.2B #1 - 46

Independent Practice