set 27-29 - San Leandro Unified School District

Lesson 27-29
NYS COMMON CORE MATHEMATICS CURRICULUM
6β€’1
T
Lesson 27: Solving Percent Problems
Student Outcomes
ο‚§
Students find the percent of a quantity. Given a part and the percent, students solve problems involving
finding the whole.
Classwork
Example (10 minutes)
Example
Solve the following three problems.
Write the words PERCENT, WHOLE, or PART under each problem to show which piece you were solving for.
πŸ”πŸŽ% of πŸ‘πŸŽπŸŽ =
πŸ”πŸŽ×πŸ‘
𝟏𝟎𝟎×πŸ‘
=
πŸπŸ–πŸŽ
πŸ”πŸŽ% of
πŸπŸ–πŸŽ
πŸ”πŸŽ×πŸ“
πŸ‘πŸŽπŸŽ
𝟏𝟎𝟎×πŸ“
πŸ“πŸŽπŸŽ
=
= πŸ‘πŸŽπŸŽ
πŸ”πŸŽ out of πŸ‘πŸŽπŸŽ =
πŸ‘πŸŽπŸŽ
πŸ”πŸŽ÷πŸ‘
πŸ“πŸŽπŸŽ
πŸ‘πŸŽπŸŽ÷πŸ‘
PART
WHOLE
=
𝟐𝟎
%
𝟐𝟎
𝟏𝟎𝟎
PERCENT
How did your solving method differ with each problem?
Solutions will vary. A possible answer may include: When solving for the part, I need to find the missing number in the
numerator. When solving for the whole, I solve for the denominator. When I solve for the percent, I need to find the
numerator when the denominator is 𝟏𝟎𝟎.
ο‚§
What are you trying to find in each example?
οƒΊ
ο‚§
How are the problems different from each other?
οƒΊ
ο‚§
Part, whole, percent
Answers will vary.
How are the problems alike?
οƒΊ
Answers will vary.
Take time to discuss the clues in each problem including the placement of the word β€œof.” The word β€œof” lets students
know which piece of information is the whole amount compared to the part. In the first example, 60% of 300 tells us
that we are looking for part of 300. Therefore, 300 is the whole. In the second example where 60% of 500 is 300,
300 is the part, and 500 is the whole. In the third example, 60 out of 300 tells us that now, 60 is the part, and 300 is
the whole. Structure the conversation around the part-whole relationship.
Lesson 27
Solving Percent Problems
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Lesson 27-29
NYS COMMON CORE MATHEMATICS CURRICULUM
6β€’1
T
ο‚§
In the first question, what is 60% of 300?
οƒΊ
Students should understand that
60
100
is the same ratio as
unknown number
300
to determine an answer of
180.
ο‚§
In this case, is 180 the part or the whole?
οƒΊ
ο‚§
180 is the part. It is part of 300.
In the second question, we are given 60% of some value equals 300 β†’
οƒΊ
ο‚§
300
?
. What is that value?
500
500 is the whole, and 300 is the part.
In the third question, we are asked, 60 out of 300 equals what percent β†’
οƒΊ
ο‚§
=
In this case, is 500 the part or the whole? What about 300? Is that a part or the whole?
οƒΊ
ο‚§
60
100
?
60
=
300 100
. What percent is that?
The percent is 20%.
In this case, is 300 the part or the whole?
οƒΊ
300 is the whole.
Exercise (20 minutes)
At this time, students break out into pairs or small groups to solve the problem.
Exercise
Use models, such as 𝟏𝟎 × πŸπŸŽ grids, ratio tables, tape diagrams, or double number line diagrams, to solve the following
situation.
Priya is doing her back-to-school shopping. Calculate all of the missing values in the table below, rounding to the nearest
penny, and calculate the total amount Priya will spend on her outfit after she receives the indicated discounts.
Shirt
(πŸπŸ“% discount)
Pants
(πŸ‘πŸŽ% discount)
Shoes
(πŸπŸ“% discount)
Necklace
(𝟏𝟎% discount)
Sweater
(𝟐𝟎% discount)
Original Price
$πŸ’πŸ’
$πŸ“πŸŽ
$πŸ”πŸŽ
$𝟐𝟎
$πŸ‘πŸ“
Amount of
Discount
$𝟏𝟏
$πŸπŸ“
$πŸ—
$𝟐
$πŸ•
Lesson 27
Solving Percent Problems
This work is derived from Eureka Math β„’ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org
This file derived from G6-M1-TE-1.3.0-07.2015
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Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
NYS COMMON CORE MATHEMATICS CURRICULUM
Lesson 27-29
6β€’1
T
What is the total cost of Priya’s outfit?
Shirt πŸπŸ“% =
πŸπŸ“
𝟏 𝟏𝟏
= =
The discount is $𝟏𝟏. The cost of the shirt is $πŸ‘πŸ‘ because $πŸ’πŸ’ βˆ’ $𝟏𝟏 = $πŸ‘πŸ‘.
𝟏𝟎𝟎 πŸ’ πŸ’πŸ’
Pants πŸ‘πŸŽ% =
πŸ‘πŸŽ
πŸπŸ“
=
The original price is $πŸ“πŸŽ. The price of the pants is $πŸ‘πŸ“ because $πŸ“πŸŽ βˆ’ $πŸπŸ“ = $πŸ‘πŸ“.
𝟏𝟎𝟎 πŸ“πŸŽ
Shoes πŸπŸ“% =
πŸπŸ“
πŸ‘
πŸ—
=
=
The original price is $πŸ”πŸŽ. The cost of the shoes is $πŸ“πŸ because $πŸ”πŸŽ βˆ’ $πŸ— = $πŸ“πŸ.
𝟏𝟎𝟎 𝟐𝟎 πŸ”πŸŽ
Necklace 𝟏𝟎% =
Sweater 𝟐𝟎% =
𝟏
𝟐
=
The discount is $𝟐. The cost of the necklace is $πŸπŸ– because $𝟐𝟎 βˆ’ $𝟐 = $πŸπŸ–.
𝟏𝟎 𝟐𝟎
𝟐𝟎
𝟏
πŸ•
= =
The original price is $πŸ‘πŸ“. The cost of the sweater is $πŸπŸ– because $πŸ‘πŸ“ βˆ’ $πŸ• = $πŸπŸ–.
𝟏𝟎𝟎 πŸ“ πŸ‘πŸ“
The total outfit would cost the following: $πŸ‘πŸ‘ + $πŸ‘πŸ“ + $πŸ“πŸ + $πŸπŸ– + $πŸπŸ– = $πŸπŸ”πŸ“.
Closing (10 minutes)
Give students time to share samples of how they solved the problem and describe the methods they chose to use when
solving.
Lesson Summary
Percent problems include the part, whole, and percent. When one of these values is missing, we can use tables,
diagrams, and models to solve for the missing number.
Lesson 27
Solving Percent Problems
This work is derived from Eureka Math β„’ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org
This file derived from G6-M1-TE-1.3.0-07.2015
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Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
NYS COMMON CORE MATHEMATICS CURRICULUM
Lesson 27-29
6β€’1
T
Lesson 28: Solving Percent Problems
Student Outcomes
ο‚§
Given a part and the percent, students find the percent of a quantity and solve problems involving finding the
whole.
Classwork
Example (5 minutes)
Read the questions from the example one by one.
Example
If an item is discounted 𝟐𝟎%, the sale price is what percent of the original price?
𝟏𝟎𝟎 βˆ’ 𝟐𝟎 = πŸ–πŸŽ
πŸ–πŸŽ%
If the original price of the item is $πŸ’πŸŽπŸŽ, what is the dollar amount of the discount?
𝟐𝟎% =
πŸ’πŸŽπŸŽ ×
𝟐𝟎
𝟐
=
𝟏𝟎𝟎 𝟏𝟎
𝟐
πŸ–πŸŽπŸŽ
=
= $πŸ–πŸŽ
𝟏𝟎
𝟏𝟎
$πŸ–πŸŽ discount
How much is the sale price?
πŸ–πŸŽ% =
πŸ’πŸŽπŸŽ ×
πŸ–πŸŽ
πŸ–
=
𝟏𝟎𝟎 𝟏𝟎
πŸ–
πŸ‘πŸπŸŽπŸŽ
=
= $πŸ‘πŸπŸŽ, or πŸ’πŸŽπŸŽ βˆ’ πŸ–πŸŽ = $πŸ‘πŸπŸŽ
𝟏𝟎
𝟏𝟎
$πŸ‘πŸπŸŽ sale price
ο‚§
What are some different ways that we can solve this question?
οƒΊ
Answers will vary. Some students may draw diagrams that they can share with the class. Others may
have found the value by finding equivalent fractions or by multiplying a quantity by the percent written
as a fraction.
Lesson 27
Solving Percent Problems
This work is derived from Eureka Math β„’ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org
This file derived from G6-M1-TE-1.3.0-07.2015
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Lesson 27-29
NYS COMMON CORE MATHEMATICS CURRICULUM
6β€’1
T
Be sure to discuss different models that could be used.
Exercise (20 minutes)
Have students work in pairs or small groups to solve the problems. Students are given the sale price and the percent
that was saved. They need to come up with the original price.
Students should create models in order to prove that their answers are correct.
Exercise
The following items were bought on sale. Complete the missing information in the table.
Item
Original Price
Sale Price
Amount of
Discount
Percent
Saved
Percent
Paid
Television
$𝟏𝟎𝟎𝟎
$πŸ–πŸŽπŸŽ
$𝟐𝟎𝟎
𝟐𝟎%
πŸ–πŸŽ%
Sneakers
$πŸ–πŸŽ
$πŸ”πŸŽ
$𝟐𝟎
πŸπŸ“%
πŸ•πŸ“%
Video Games
$πŸ”πŸŽ
$πŸ“πŸ’
$πŸ”
𝟏𝟎%
πŸ—πŸŽ%
MP3 Player
$πŸ–πŸ”
$πŸ“πŸ. πŸ”πŸŽ
$πŸ‘πŸ’. πŸ’πŸŽ
πŸ’πŸŽ%
πŸ”πŸŽ%
Book
$πŸπŸ’. 𝟎𝟎
$𝟏𝟏. 𝟐𝟎
$𝟐. πŸ–πŸŽ
𝟐𝟎%
πŸ–πŸŽ%
Snack Bar
$𝟐. 𝟎𝟎
$𝟏. πŸ•πŸŽ
$𝟎. πŸ‘πŸŽ
πŸπŸ“%
πŸ–πŸ“%
Closing (10 minutes)
ο‚§
Have students showcase some of the models used to solve the problems. One possible way to showcase the
work, if time allows, would be to hang the work on the walls and have students do a gallery walk to view the
diagrams. Ask students how they could check their work.
οƒΊ
The answers may vary according to which values are given and which values are missing. Students may
mention that the discount and the sale price should add to be the original amount. The percents should
add to 100%. They could solve the problem using the answer to see if they can work back to a given
amount.
Lesson Summary
Percent problems include the part, whole, and percent. When one of these values is missing, we can use tables,
diagrams, and models to solve for the missing number.
Lesson 27
Solving Percent Problems
This work is derived from Eureka Math β„’ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org
This file derived from G6-M1-TE-1.3.0-07.2015
219
This work is licensed under a
Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
Lesson 27-29
NYS COMMON CORE MATHEMATICS CURRICULUM
6β€’1
T
Lesson 29: Solving Percent Problems
Student Outcomes
ο‚§
Students find the percent of a quantity.
ο‚§
Given a part and the percent, students solve problems involving finding the whole.
Classwork
Exploratory Challenges (25 minutes): Group/Partner
Students explore what it means to have 10%. Students recognize the equivalence between 10%,
10
100
, and
1
10
and use
this relationship to quickly calculate 10% of different quantities. Being able to calculate 10% of a quantity can be an
efficient tool or strategy when calculating other percents.
Exploratory Challenge 1
Claim: To find 𝟏𝟎% of a number, all you need to do is move the decimal to the left once.
Use at least one model to solve each problem (e.g., tape diagram, table, double number line diagram, 𝟏𝟎 × πŸπŸŽ grid).
a.
Make a prediction. Do you think the claim is true or false?
Explain why.
Answers will vary. One could think the claim is true because 𝟏𝟎% as a fraction is
happens when one divides by 𝟏𝟎 or multiplies by
𝟏
𝟏
. The same thing
𝟏𝟎
. A student may think the claim is false because it
𝟏𝟎
depends on what whole amount represents the number from which the percentage is taken.
Determine 𝟏𝟎% of πŸ‘πŸŽπŸŽ.
b.
πŸ‘πŸŽπŸŽ ×
πŸ‘πŸŽ
𝟏
πŸ‘πŸŽπŸŽ
=
= πŸ‘πŸŽ
𝟏𝟎
𝟏𝟎
𝟏𝟎% of
e.
𝟏
πŸ–πŸŽ
=
=πŸ–
𝟏𝟎 𝟏𝟎
Find 𝟏𝟎% of πŸ“.
πŸ“×
πŸ’πŸ–πŸŽ
πŸ–
𝟏
πŸ”. πŸ’
𝟏
πŸ”πŸ’ ×
= πŸ”. πŸ’
𝟏𝟎
f.
Find 𝟏𝟎% of πŸ–πŸŽ.
πŸ–πŸŽ ×
Determine 𝟏𝟎% of πŸ”πŸ’.
d.
c.
is πŸ’πŸ–.
g.
𝟐
𝟏
πŸ“
𝟏
=
=
𝟏𝟎 𝟏𝟎 𝟐
𝟏𝟎% of
πŸ”πŸŽ
is πŸ”.
πŸ” × πŸπŸŽ = πŸ”πŸŽ
πŸ’πŸ–
πŸ’πŸ–
πŸ’πŸ–
πŸ’πŸ–
πŸ’πŸ–
πŸ’πŸ–
πŸ’πŸ–
πŸ’πŸ–
πŸ’πŸ–
πŸ’πŸ–
πŸ’πŸ– × πŸπŸŽ = πŸ’πŸ–πŸŽ
Lesson 27
Solving Percent Problems
This work is derived from Eureka Math β„’ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org
This file derived from G6-M1-TE-1.3.0-07.2015
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Lesson 27-29
NYS COMMON CORE MATHEMATICS CURRICULUM
6β€’1
T
h.
Gary read πŸ‘πŸ’ pages of a πŸ‘πŸ’πŸŽ pages book. What percent did he read?
πŸ‘πŸ’ ÷ πŸ‘πŸ’
𝟏
𝟏𝟎
=
=
= 𝟏𝟎%
πŸ‘πŸ’πŸŽ ÷ πŸ‘πŸ’ 𝟏𝟎 𝟏𝟎𝟎
i.
Micah read πŸπŸ” pages of his book. If this is 𝟏𝟎% of the book, how many pages are in the book?
𝟏𝟎
𝟏 × πŸπŸ”
πŸπŸ”
=
=
𝟏𝟎𝟎 𝟏𝟎 × πŸπŸ” πŸπŸ”πŸŽ
There are πŸπŸ”πŸŽ pages in the book.
j.
Using the solutions to the problems above, what conclusions can you make about the claim?
The claim is true. When I find 𝟏𝟎% of a number, I am really finding
𝟏
𝟏𝟎
of the amount or dividing by 𝟏𝟎,
which is the same as what occurred when I moved the decimal point in the number one place to the left.
ο‚§
Using the solutions to the problems above, what conclusions can you make about the claim?
οƒΊ
Answers will vary. However, students are required to share what is mathematically happening when
the decimal is moved over once to help make connections to why it works. Students may relate back to
using place value and regrouping with the concept of decimals.
Students read a claim that two separate discounts give the same results as the sum of the two discounts taken off the
original price at the same time. Students need to conclude that they are not the same because the second discount is
being taken off a new amount not the original price.
Exploratory Challenge 2
Claim: If an item is already on sale, and then there is another discount taken off the sale price, this is the same as taking
the sum of the two discounts off the original price.
Use at least one model to solve each problem (e.g., tape diagram, table, double number line diagram, 𝟏𝟎 × πŸπŸŽ grid).
a.
Make a prediction. Do you think the claim is true or false? _____________ Explain.
The answer is false. They will be different because when two discounts are taken off, the second discount is
taken off a new amount.
b.
Sam purchased πŸ‘ games for $πŸπŸ’πŸŽ after a discount of πŸ‘πŸŽ%. What was the original price?
𝟐𝟎
𝟐𝟎
𝟐𝟎
𝟐𝟎
Sale price: $πŸπŸ’πŸŽ
𝟐𝟎
𝟐𝟎
𝟐𝟎
𝟐𝟎
𝟐𝟎
𝟐𝟎
Discount: $πŸ”πŸŽ
$𝟐𝟎𝟎 is the original price.
c.
If Sam had used a 𝟐𝟎% off coupon and opened a frequent shopper discount membership to save 𝟏𝟎%, would
the games still have a total of $πŸπŸ’πŸŽ?
𝟐𝟎% =
𝟐𝟎
𝟐
=
𝟏𝟎𝟎 𝟏𝟎
Lesson 27
$𝟐𝟎𝟎 ×
𝟐
𝟏𝟎
=
Solving Percent Problems
This work is derived from Eureka Math β„’ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org
This file derived from G6-M1-TE-1.3.0-07.2015
$πŸ’πŸŽπŸŽ
𝟏𝟎
= $πŸ’πŸŽ saved. The price after the coupon is $πŸπŸ”πŸŽ.
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Lesson 27-29
NYS COMMON CORE MATHEMATICS CURRICULUM
6β€’1
T
𝟏𝟎% =
𝟏𝟎
𝟏
=
𝟏𝟎𝟎 𝟏𝟎
$πŸπŸ”πŸŽ ×
𝟏
$πŸπŸ”πŸŽ
=
= $πŸπŸ” saved. The price after the coupon and
𝟏𝟎
𝟏𝟎
discount membership is $πŸπŸ’πŸ’.
No, the games would now total $πŸπŸ’πŸ’.
d.
Do you agree with the claim?
support your claim.
NO
Explain why or why not. Create a new example to help
When two discounts are taken off, the shopper pays more than if both were added together and taken off.
Example:
$𝟏𝟎𝟎 original price
𝟐𝟎%:
𝟏𝟎𝟎 ×
Two 𝟏𝟎% off discounts:
𝟐
𝟏𝟎
=
𝟐𝟎𝟎
𝟏𝟎
= 𝟐𝟎 saved
$𝟏𝟎𝟎 βˆ’ $𝟐𝟎 = $πŸ–πŸŽ sale price
𝟏𝟎𝟎 ×
πŸ—πŸŽ ×
𝟏
𝟏𝟎
𝟏
𝟏𝟎
=
=
𝟏𝟎𝟎
𝟏𝟎
πŸ—πŸŽ
𝟏𝟎
= 𝟏𝟎
=πŸ—
$𝟏𝟎𝟎 βˆ’ $𝟏𝟎 βˆ’ $πŸ— = $πŸ–πŸ sale price
Closing (15 minutes)
Give students time to share samples of how they solved the problem. Take time to point out similarities in the different
models. Ask students to reflect on which models they like to use most and why.
Lesson Summary
Percent problems have three parts: whole, part, percent.
Percent problems can be solved using models such as ratio tables, tape diagrams, double number line diagrams, and
𝟏𝟎 × πŸπŸŽ grids.
.
Lesson 27
Solving Percent Problems
This work is derived from Eureka Math β„’ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org
This file derived from G6-M1-TE-1.3.0-07.2015
222
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Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.