Transcript Lesson 3 MI/Vocab

• Use proportions to solve problems.
• equivalent ratios
• proportion
• cross products
• constant of proportionality
Interactive Lab:
Solving Problems
Write and Solve a Proportion
CLOTHING Melvin can decorate 8 t-shirts in 3
hours. At this rate, write and solve a proportion to
find the time it will take him to decorate 20 t-shirts.
Write a proportion. Let t represent the time in hours.
shirts
time
shirts
time
Write and Solve a Proportion
Write the proportion.
Find the cross products.
Multiply.
Divide each side by 8.
Simplify.
Answer: It will take Melvin 7.5 hours to decorate 20
t-shirts.
CLOTHING Adrian can decorate 5 t-shirts in 2 hours.
At this rate, write and solve a proportion to find the
time it will take her to decorate 18 t-shirts.
A. 6.5 hours
B. 7 hours
C. 7.2 hours
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D
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C
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B
D. 7.6 hours
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B.
C.
D.
A
B
C
D
COOKING A recipe serves 10 people and calls for 3
cups of flour. If you want to make the recipe for 15
people, how many cups of flour should you use?
Write a proportion. Let c represent the number of cups
of flour needed to serve 15 people.
cups of flour
total people served
cups of flour
total people served
Find the cross products.
Multiply.
Divide each side by 10.
Simplify.
Answer: You will need 4.5 cups of flour to make the
recipe for 15 people.
COOKING A recipe serves 12 people and calls for 5
cups of sugar. If you want to make the recipe for 18
people, how many cups of sugar should you use?
A. 6.5 cups
B. 6.7 cups
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2.
3.
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0%
C. 7.2 cups
D. 7.5 cups
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B
C
D
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B
C
D
Write and Use an Equation
FOOD Haley bought 4 pounds of tomatoes for
$11.96. Write an equation relating the cost to the
number of pounds of tomatoes. How much would
Haley pay for 6 pounds at this same rate? for 10
pounds?
Find the constant of proportionality between cost and
pounds.
The cost is $2.99
per pound.
Write and Use an Equation
Words
The cost is $2.99 times the number of pounds.
Variable
Let c represent the cost.
Let p represent the number of pounds.
Equation
c = 2.99 ● p
Use this same equation to find the cost for 6 and 10
pounds of tomatoes sold at the same rate.
Write and Use an Equation
Write the equation.
Replace p with the
number of pounds.
Multiply.
Answer: The cost for 6 pounds of tomatoes is $17.94
and for 10 pounds is $29.90.
FOOD Cameron bought 3 pounds of apples for
$11.37. Write an equation relating the cost to the
number of pounds of apples. How much would
Cameron pay for 5 pounds at this same rate?
A. $18.95
B. $19.20
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3.
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0%
C. $19.85
D. $20.15
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B
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D
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B
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• TEETH: For every 6 people who say they floss
daily, there are 14 people who say they do not.
Write and Solve a proportion to determine out of
50 people how many you would expect to say
they do floss daily.
• ILLNESS: For every person who actually has the
flu, there are 5 people who have the same
symptoms but with only a cold. If a doctor sees
60 patients, write and solve a proportion to
determine how many of these you would expect
to only have a cold.
• PHOTOGRAPHY: It takes 3 minutes to print out 4
digital photos. Write an equation relating the
number of photos, n, to the number of minutes,
m.
• At this rate, how long will it take to print 10
photos?