02/09/11 Proportions & Percent Today’s Plan: -Warm-up -Intro to Percent -Assignment LT: I will...

02/09/11 Proportions & Percent

Today’s Plan:-Warm-up-Intro to Percent-Assignment

LT: I will apply my understanding of ratios to solve problems involving proportional relationships, including percent.

Warm Up

Sara, Jim, and Laura worked different hours at the ski swap. They agreed to split the $600 they earned in a ratio of 5:3:2 respectively. How much did each student get?

02/09/11 Proportions & Percent

Today’s Plan:-Warm-up-Intro to Percent-Assignment

LT: I will apply my understanding of ratios to solve problems involving proportional relationships, including percent.

Percent!

Course 2

6-1 Fractions, Decimals, and Percents

The students at Westview Middle School are collecting cans of food for the local food bank. Their goal is to collect 2,000 cans in one month. After 10 days, they have 800 cans of food. What percent of their goal have they reached?

Course 2


0 200 400 600 800 1,000 1,200 1,400 1,600 1,800 2,000

0 15

25

35

45

55

00 0.2 0.4 0.6 0.8 1.0

0 20% 40% 60% 80% 100%

The number lines show that the students have reached 40% of their goal.

Course 2


The word percent means “per hundred.” So 40% means “40 out of 100.”

Reading Math

A percent is the ratio of a number to 100. The symbol % is used to indicate that a number is a percent. For example, 40% is

the ratio 40 to 100, or . Percents can be

written as fractions or decimals

40100

Write 88% as a fraction in simplest form.

Additional Example 1: Writing Percents as Fractions

Course 2


88% = 88100

Write the percent as a fraction with adenominator of 100.

= 2225

Simplify.

Write 45% as a fraction in simplest form.

Try This: Example 1

Course 2


45% = 45100

Write the percent as a fraction with adenominator of 100.

= 920

Simplify.

Additional Example 2: Writing Percents as Decimals

Course 2


Write 51% as a decimal.

51% = 51100

= 0.51

Write the percent as a fraction with a denominator of 100.

Write the fraction as a decimal.

Try This: Example 2

Course 2


Write 67% as a decimal.

67% = 67100

= 0.67

Write the percent as a fraction with a denominator of 100.

Write the fraction as a decimal.

Course 2

6-1 Fractions, Decimals, and Percent

Notice that both 43% and 0.43 mean “43 hundredths.” Another way to write a percent as a decimal is to delete the percent sign and move the decimal point two places to the left.

43.% = 0.43

Write each decimal as a percent.

Additional Example 3A & 3B: Writing Decimals as Percents

Course 2


A. 0.08

= 8%

B. 0.7

= 70%

Write the decimal as a fraction.

Write the fraction as a percent.


Write an equivalent fraction with adenominator of 100.


0.08 =8

100

0.7 = 710

70100

=

Write each decimal as a percent.

Try This: Example 3A & 3B

Course 2


A. 0.01

= 1%

B. 0.1

= 10%




Write an equivalent fraction with adenominator of 100.


0.01 =1

100

0.1 = 110

10100

=

Course 2

6-1 Fractions, Decimals, and Percent

Both 0.07 and 7% mean “7 hundredths.” you can write a decimal as a percent by moving the decimal point two places to the right and adding the percent sign.

0.07 = 7.0%

Course 2

6-1 Fractions, Decimals and Percents

Write each fraction as a percent.

A. 35

35

= 3 · 205 · 20

= 60100

= 60%

Write an equivalent fraction with a denominator of 100.


The method shown in example 4A works only if the given denominator is a factor or multiple of 100.

Helpful Hint

Additional Example 4A: Writing Fractions as Decimals


Additional Example 4B: Writing Fractions as Decimals

Course 2


B. 740

740

= 7 ÷ 40

= 0.175

= 17.5%

Use division to write a fraction as adecimal.

Write the decimal as a percent.

The method shown in 4B works for any denominator.

Helpful Hint

Course 2

6-1 Fractions, Decimals and Percents


A. 34

34

= 3 · 254 · 25

= 75100

= 75%

Write an equivalent fraction with a denominator of 100.


Try This: Example 4A


Try This: Example 4B

Course 2


B. 960

960

= 9 ÷ 60

= 0.15

= 15%

Use division to write a fraction as adecimal.

Write the decimal as a percent.

Lesson Quiz

65%

Insert Lesson Title Here

0.72

60%

Course 2


1. Write 40% as a fraction.

2. Write 0.65 as a percent.

3. Write 72% as a decimal.

4. Write as a percent. 610

5. About 95% of all animals are insects. Express this percent as a fraction.

25

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02/09/11 Proportions & Percent Today’s Plan: -Warm-up -Intro to Percent -Assignment LT: I will...

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