Transcript percent - West Windsor-Plainsboro Regional School District

2-9
Percents
Objective:
To solve problems involving percents.
Warm up:
- Take out HW & Indirect Measurement Lab
- Check your HW answers.
Holt McDougal Algebra 1
2-9
Percents
Agenda
1. Check HW answers – Any questions?
2. Review the Indirect Measurement
Homework
3. Equivalence Game
4. (2.9) Lesson & Guided Notes
5. Practice
6. Pass back quizzes
Holt McDougal Algebra 1
2-9
Percents
Lesson Starter (2-9)
Percent to decimal:
•Divide by 100 (move decimal
two places to the left.)
Decimal to percent:
• Multiply by 100 (move decimal two
places to the right.)
Decimal to fraction:
• Use the place value to write a
fraction. Simplify.
**Fraction to percent:**
• Divide the numerator by the
denominator.
• Multiply by 100.
Holt McDougal Algebra 1
2-9
Percents
A percent is a special ratio that compares
a number to 100. Ex,
Equivalent Percent, Fraction & Decimal: Ex
Holt McDougal Algebra 1
2-9
Percents
Some Common Equivalents
Percent 10% 20% 25%
Fraction
Decimal
Holt McDougal Algebra 1
40% 50% 60%
75% 80%100%
2-9
Percents
Strengthen your Skills!
Equivalent fraction, decimal and percent
matching.
•You will have 5 minutes to match and group
equivalent fractions, decimals & percents.
•Record your time in your notes.
•If you complete the entire activity in under 5 minutes,
mix up your cards and repeat! See if you can beat your
personal best time!
Holt McDougal Algebra 1
2-9
Percents
Complete Guided Notes
See Document Camera
Holt McDougal Algebra 1
2-9
Percents
Percent Problems: Review
For questions like….
1.Find 30% of 80.
2.What percent of 60 is 15?
3.40% of what number is 14?
There are two main methods to solve.
Method 1 Use a proportion.
Holt McDougal Algebra 1
OR
Method 2 Use an equation.
2-9
Percents
A closer look at :
Holt McDougal Algebra 1
2-9
Percents
Example 1
What percent of 35 is 7?.
Method 1 Use a proportion.
Use the percent proportion.
Let x represent the percent.
35x = 700
x = 20
7 is 20% of 35.
Holt McDougal Algebra 1
Find the cross products.
Since x is multiplied by 35, divide
both sides by 35 to undo the
multiplication.
2-9
Percents
Example 2
Find 210% of 8.
Method 2 Use an equation.
x = 210% of 8
x = 2.10(8)
x = 16.8
210% of 8 is 16.8.
Holt McDougal Algebra 1
Write an equation. Let x
represent the part.
Write the percent as a decimal
and multiply.
2-9
Percents
Example 3: Application
The serving size of a popular orange drink is
12 oz. The drink is advertised as containing
5% orange juice. How many ounces of orange
juice are in one serving size?
Use the percent proportion.
Let x represent the part.
100x = 60
Find the cross products.
Since x is multiplied by 100, divide
both sides by 100 to undo the
multiplication.
x = 0.6
A 12 oz orange drink contains 0.6 oz of orange juice.
Holt McDougal Algebra 1
2-9
Percents
Some common misconceptions…
Even though a percent is the ratio of a
number out of 100 – they can be greater
than 100%!!
For example: 120% =
= 1.2
You can also find percents that are less
than 1%.
For example, 0.5%=
Holt McDougal Algebra 1
= 0.005
2-9
Percents
Holt McDougal Algebra 1
2-9
Percents
Lesson Starter (2-9)
What do you notice about each of
these proportions?
Holt McDougal Algebra 1
2-9
Percents
Objective:
To solve problems involving percents.
Warm up:
- Take out HW.
- Complete the following.
Holt McDougal Algebra 1
2-9
Percents
Percent Problems: Review
For questions like….
1.Find 30% of 80.
2.What percent of 60 is 15?
3.40% of what number is 14?
There are two main methods to solve.
Method 1 Use a proportion.
Holt McDougal Algebra 1
OR
Method 2 Use an equation.
2-9
Percents
A closer look at :
Holt McDougal Algebra 1
2-9
Percents
Example 1
What percent of 35 is 7?.
Method 1 Use a proportion.
Use the percent proportion.
Let x represent the percent.
35x = 700
x = 20
7 is 20% of 35.
Holt McDougal Algebra 1
Find the cross products.
Since x is multiplied by 35, divide
both sides by 35 to undo the
multiplication.
2-9
Percents
Example 2
Find 210% of 8.
Method 2 Use an equation.
x = 210% of 8
x = 2.10(8)
x = 16.8
210% of 8 is 16.8.
Holt McDougal Algebra 1
Write an equation. Let x
represent the part.
Write the percent as a decimal
and multiply.
2-9
Percents
Example 3: Application
The serving size of a popular orange drink is
12 oz. The drink is advertised as containing
5% orange juice. How many ounces of orange
juice are in one serving size?
Use the percent proportion.
Let x represent the part.
100x = 60
Find the cross products.
Since x is multiplied by 100, divide
both sides by 100 to undo the
multiplication.
x = 0.6
A 12 oz orange drink contains 0.6 oz of orange juice.
Holt McDougal Algebra 1
2-9
Percents
Lets practice!
You choose:
1.Mini Lesson with Ms. Hornick.
(Strategies for tackling these
problems.)
2.Independent Practice
Percent Problems &
Applications
Holt McDougal Algebra 1
2-9
Percents
Equivalence Activity!
Beat your time from yesterday!
Holt McDougal Algebra 1
2-9
Percents
2.10 Applications
Holt McDougal Algebra 1
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Percents
Exit Ticket:
Find each value. Round to the nearest tenth if
necessary.
1. Find 20% of 80. 16
2. 35% of what number is 40?
3. 120 is what percent of 80?
114.3
150%
4. A survey at a local school showed that
38% of the students chose chocolate ice
cream as their favorite ice cream. Eight
hundred students took the survey. How
many chose chocolate ice cream?
304
Holt McDougal Algebra 1