Lesson 10: A Critical Look at Proportional Relationships

Lesson 10
NYS COMMON COR E MATHEMATICS CURRICULUM
8β€’4
Lesson 10: A Critical Look at Proportional Relationships
Exit Ticket Sample Solutions
Alex skateboards at a constant speed from his house to school πŸ‘.πŸ– miles away. It takes him πŸπŸ– minutes.
a.
What fraction represents his constant speed, π‘ͺ?
πŸ‘. πŸ–
=π‘ͺ
πŸπŸ–
b.
After school, Alex skateboards at the same constant speed to his friend’s house. It takes him 𝟏𝟎 minutes.
Write the fraction that represents constant speed, π‘ͺ, if he travels a distance of π’š.
π’š
=π‘ͺ
𝟏𝟎
c.
Write the fractions from parts (a) and (b) as a proportion, and solve to find out how many miles Alex’s
friend’s house is from school. Round your answer to the tenths place.
πŸ‘.πŸ–
π’š
=
πŸπŸ– 𝟏𝟎
πŸ‘. πŸ– (𝟏𝟎) = πŸπŸ–π’š
πŸ‘πŸ– = πŸπŸ–π’š
πŸ‘πŸ–
=π’š
πŸπŸ–
𝟐.𝟏 β‰ˆ π’š
Alex’s friend lives about 𝟐.𝟏 miles from school.
Lesson 10:
A Critical Look at Proportional Relationships
This work is derived from Eureka Math β„’ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org
This file derived from G8-M4-TE-1.3.0-09.2015
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Lesson 10
NYS COMMON COR E MATHEMATICS CURRICULUM
8β€’4
Problem Set Sample Solutions
Students practice writing and solving proportions to solve constant speed problems. Students write two variable
equations to represent situations, generally.
1.
Eman walks from the store to her friend’s house, 𝟐 miles away. It takes her πŸ‘πŸ“ minutes.
a.
What fraction represents her constant speed, π‘ͺ?
𝟐
=π‘ͺ
πŸ‘πŸ“
b.
Write the fraction that represents her constant speed, π‘ͺ, if she walks π’š miles in 𝟏𝟎 minutes.
π’š
=π‘ͺ
𝟏𝟎
c.
Write and solve a proportion using the fractions from parts (a) and (b) to determine how many miles she
walks after 𝟏𝟎 minutes. Round your answer to the hundredths place.
𝟐
π’š
=
πŸ‘πŸ“ 𝟏𝟎
πŸ‘πŸ“π’š = 𝟐𝟎
πŸ‘πŸ“
𝟐𝟎
π’š=
πŸ‘πŸ“
πŸ‘πŸ“
π’š = 𝟎. πŸ“πŸ•πŸπŸ’πŸβ€¦
Eman walks about 𝟎. πŸ“πŸ• miles after 𝟏𝟎 minutes.
d.
Write a two-variable equation to represent how many miles Eman can walk over any time interval.
Let π’š represent the distance Eman walks in 𝒙 minutes.
𝟐
π’š
=
πŸ‘πŸ“ 𝒙
πŸ‘πŸ“π’š = πŸπ’™
πŸ‘πŸ“
𝟐
π’š=
𝒙
πŸ‘πŸ“
πŸ‘πŸ“
𝟐
π’š=
𝒙
πŸ‘πŸ“
2.
Erika drives from school to soccer practice 𝟏. πŸ‘ miles away. It takes her πŸ• minutes.
a.
What fraction represents her constant speed, π‘ͺ?
𝟏. πŸ‘
=π‘ͺ
πŸ•
b.
What fraction represents her constant speed, π‘ͺ, if it takes her 𝒙 minutes to drive exactly 𝟏 mile?
𝟏
=π‘ͺ
𝒙
c.
Write and solve a proportion using the fractions from parts (a) and (b) to determine how much time it takes
her to drive exactly 𝟏 mile. Round your answer to the tenths place.
𝟏.πŸ‘ 𝟏
=
πŸ•
𝒙
𝟏. πŸ‘π’™ = πŸ•
Lesson 10:
A Critical Look at Proportional Relationships
This work is derived from Eureka Math β„’ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org
This file derived from G8-M4-TE-1.3.0-09.2015
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This work is licensed under a
Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
Lesson 10
NYS COMMON COR E MATHEMATICS CURRICULUM
8β€’4
𝟏.πŸ‘
πŸ•
𝒙=
𝟏.πŸ‘
𝟏. πŸ‘
𝒙 = πŸ“. πŸ‘πŸ–πŸ’πŸ”πŸβ€¦
It takes Erika about πŸ“.πŸ’ minutes to drive exactly 𝟏 mile.
d.
Write a two-variable equation to represent how many miles Erika can drive over any time interval.
Let π’š be the number of miles Erika travels in 𝒙 minutes.
𝟏. πŸ‘ π’š
=
πŸ•
𝒙
πŸ•π’š = 𝟏.πŸ‘π’™
πŸ•
𝟏.πŸ‘
π’š=
𝒙
πŸ•
πŸ•
𝟏.πŸ‘
π’š=
𝒙
πŸ•
3.
Darla drives at a constant speed of πŸ’πŸ“ miles per hour.
a.
If she drives for π’š miles and it takes her 𝒙 hours, write the two-variable equation to represent the number of
miles Darla can drive in 𝒙 hours.
π’š
= πŸ’πŸ“
𝒙
π’š = πŸ’πŸ“π’™
b.
Darla plans to drive to the market πŸπŸ’ miles from her house, then to the post office πŸ‘ miles from the market,
and then return home, which is πŸπŸ“ miles from the post office. Assuming she drives at a constant speed the
entire time, how long will it take her to run her errands and get back home? Round your answer to the
hundredths place.
Altogether, Darla plans to drive πŸ‘πŸ miles because πŸπŸ’ + πŸ‘ + πŸπŸ“ = πŸ‘πŸ.
πŸ‘πŸ = πŸ’πŸ“π’™
πŸ‘πŸ πŸ’πŸ“
=
𝒙
πŸ’πŸ“ πŸ’πŸ“
𝟎.πŸ•πŸπŸπŸπŸβ€¦ = 𝒙
It will take Darla about 𝟎.πŸ•πŸ hours to run her errands and get back home.
4.
Aaron walks from his sister’s house to his cousin’s house, a distance of πŸ’ miles, in πŸ–πŸŽ minutes. How far does he
walk in πŸ‘πŸŽ minutes?
I cannot say for sure how far Aaron walks in πŸ‘πŸŽ minutes because I do not know if he is walking at a constant speed.
Maybe he stopped at his friend’s house for 𝟐𝟎 minutes.
5.
Carlos walks πŸ’ miles every night for exercise. It takes him exactly πŸ”πŸ‘ minutes to finish his walk.
a.
Assuming he walks at a constant rate, write an equation that represents how many miles, π’š, Carlos can walk
in 𝒙 minutes.
Since
πŸ’
πŸ”πŸ‘
= π‘ͺ and
π’š
𝒙
= π‘ͺ, then
πŸ’
π’š
=
πŸ”πŸ‘ 𝒙
πŸ”πŸ‘π’š = πŸ’π’™
Lesson 10:
A Critical Look at Proportional Relationships
This work is derived from Eureka Math β„’ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org
This file derived from G8-M4-TE-1.3.0-09.2015
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This work is licensed under a
Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
Lesson 10
NYS COMMON COR E MATHEMATICS CURRICULUM
8β€’4
πŸ”πŸ‘
πŸ’
π’š=
𝒙
πŸ”πŸ‘
πŸ”πŸ‘
πŸ’
π’š=
𝒙.
πŸ”πŸ‘
b.
Use your equation from part (a) to complete the table below. Use a calculator, and round all values to the
hundredths place.
𝒙 (minutes)
Linear Equation:
πŸ’
π’š=
𝒙
πŸ”πŸ‘
π’š (miles)
πŸπŸ“
π’š=
πŸ’
( πŸπŸ“ )
πŸ”πŸ‘
𝟎.πŸ—πŸ“
πŸ‘πŸŽ
π’š=
πŸ’
( πŸ‘πŸŽ )
πŸ”πŸ‘
𝟏.πŸ—πŸŽ
πŸ’πŸŽ
π’š=
πŸ’
( πŸ’πŸŽ )
πŸ”πŸ‘
𝟐.πŸ“πŸ’
πŸ”πŸŽ
π’š=
πŸ’
( πŸ”πŸŽ )
πŸ”πŸ‘
πŸ‘.πŸ–πŸ
πŸ•πŸ“
π’š=
πŸ’
( πŸ•πŸ“ )
πŸ”πŸ‘
πŸ’.πŸ•πŸ”
Lesson 10:
A Critical Look at Proportional Relationships
This work is derived from Eureka Math β„’ and licensed by Great Minds. ©2015 Great Minds. eureka-math.org
This file derived from G8-M4-TE-1.3.0-09.2015
115
This work is licensed under a
Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.