Welcome to this IRSC Adult Education Live Virtual Lesson

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Welcome to this IRSC Adult Education Live Virtual
Lesson

• Diana Lenartiene, Ed. S. moderator/instructor

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Introducing your virtual classroom
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Ratios
We will now view a video on Ratio
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Ratios

• A ratio is a comparison between two numbers by
  division.
• It can be written in three different ways

5 to 2
5 2
5
2
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Equal Ratios

• When two ratios name the same number, they are
  equal. Its like writing an equivalent fraction.

20 30
Equal Ratios
80 120
2 3
10 15
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Ratios in Simplest Form

• Ratios can be written in simplest form.
• Divide both terms in the ratio by their GCF.

12/8 3/2 We have reduced the
fraction to lowest terms. To
do that, we divided
the numerator and denominator
by 4.
Example 12 to 8
3 to 2
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Understanding Proportions
We will now watch a video on proportion
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Vocabulary

• A proportion is an equation stating that two
  ratios are equal.

To prove that two ratios form a proportion, you
must prove that they are equivalent. To do this,
you must demonstrate that the relationship
between numerators is the same as the
relationship between denominators.
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Examples Do the ratios form a proportion?
Yes, these two ratios DO form a proportion,
because the same relationship exists in both the
numerators and denominators.
,
4
8
2
,
No, these ratios do NOT form a proportion,
because the ratios are not equal.
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3
3
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Completing a Proportion

• Determine the relationship between two numerators
  or two denominators (depending on what you have).
• Execute that same operation to find the part you
  are missing.

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Example Cross multiply to see if they are equal!

1. 7
2. 8

Multiply 3 x 8 24 Multiply 4 x 7 28 These
ratios are NOT a proportion! Why? Because they
were not equal
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Using Cross Products
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Cross Products

• When you have a proportion (two equal ratios),
  then you have equivalent cross products.
• Find the cross product by multiplying the
  denominator of each ratio by the numerator of the
  other ratio.

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Example Do the ratios form a proportion? Check
using cross products.
4
3
,
12
9
These two ratios DO form a proportion because
their cross products are the same.
12 x 3 36
9 x 4 36
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Example 2
5
2
,
8
3
No, these two ratios DO NOT form a proportion,
because their cross products are different.
8 x 2 16
3 x 5 15
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Solving a Proportion Using Cross Products

• Use the cross products to create an equation.
• Solve the equation for the variable using the
  inverse operation.

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Example Solve the Proportion
20
k
Start with the variable.

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68
Simplify.
Now we have an equation. To get the k by itself,
divide both sides by 68.
17(20)

68 K

340
68 K
68
68
k
5
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Word Problems
We will now view a video showing how to Set up
and solve word problems using the Proportion
formula.
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What we have learned

• A ratio shows the relation ship of tow things as
  a
• Fraction.
• A proportion is a statement that two ratios are
  equal
• Proportions allow us to solve problems by using
  the
• Proportion formula.
• We can set up proportions to solve real world
  math
• Problems.

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Now, you need to make a copy of this screen to
send to your teacher for proof of Attendance.
This can be done in three easy steps
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If you still have questions, please contact me
at dlenarti_at_irsc.edu

• Thank you for viewing this presentation.
• Diana Lenartiene, IRSC ABE Instructor