Transcript Solving Proportions

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Objective
Solve proportions
Vocabulary
Proportion
When two ratios are equivalent
Vocabulary
Cross product
The product of the numerator of one ratio and
the denominator of the other ratio
Example 1 Identify a Proportion
Example 2 Identify a Proportion
Example 3 Solve Proportions
Example 4 Solve Proportions
Determine whether
and
form a proportion.
Write a proportion.
Find the cross products.
8(3) =? 12(2)
Multiply.
24 = 24
Check to see if equation is equal
The cross products are equal
Answer: The ratios form a proportion
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Determine whether
and
form a proportion.
Answer: The ratios do not form a proportion
1/4
Determine whether
and
form a proportion.
Write a proportion
Find the cross products.
5(32) =? 8(18)
Multiply.
Check to see if equation is equal
The cross products are not equal
Answer: The ratios do not form a proportion
2/4
Determine whether
and
form a proportion.
Answer: The ratios form a proportion
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Write the proportion.
Solve
Find the cross products.
Multiply.
Ask “what is being done to the
variable?”
The variable (n) is being
multiplied by 3.5
Do inverse on both sides
1  n = 24
Combine “like” terms
3/4
Solve
Use the Identity Property to
multiply 1  n
1  n = 24
Answer: n = 24
3/4
Solve
Answer: x = 25
3/4
FLAGS According to specifications, the ratio of the
length of the U.S. flag to its width must be 1.9 to 1.
How long must a U.S. flag be if it is designed to have a
width of 2.5 feet?
Write a proportion.
length →
width →
Find the cross products.
Multiply.
Add dimensional analysis
Answer: L = 4.75 feet
4/4
*
SCHOOL The ratio of boys to girls at Blue Hills Middle
School is 4 to 5. How many girls attend the school if
there are 96 boys?
Answer: x = 120 girls
4/4
Lesson 7:3
Assignment
Algebra: Solving
Proportions
16 - 39 All