Download Solving the proportion

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What Are You Learning?
I CAN solve
proportions.
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Why Do You Need To Know This?

Proportions can be used to compare
different types of items.

Proportions are useful because they
allow objects to be compared equally.

They can be used many ways in the real
world.
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Vocabulary

Proportion—an equation that shows
that two ratios are equivalent.

Cross Product—the product of the
numerator of one ratio and the
denominator of the other ratio.
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Notes
1=3
2 6
1 x 6 is a cross product.
2 x 3 is a cross product.

The cross products of a proportion are equal.

Two ratios form a proportion if their cross
products are equal.
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Determine whether each pair of ratios form
a proportion.
d. 25/40 and 5/8
a. ¾ and 9/12
b.
c.
8/12 and 14/21
4/5 and 5/6
e.
13/15 and 4/5
f.
49/21 and 28/12
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Notes
 Solving
the proportion—
Process of using cross products
to find a missing term in a
proportion.
 Solving
a proportion is similar to
solving an equation.
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Example
x = 4
9
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x • 6 = 9 • 4 (Cross multiply)
6x = 36 (Solve for the variable)
6x = 36 (Divide to undo multiplication
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6
x=6
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Solve each proportion.
When necessary, round to the nearest tenth.
a.
15/30 = n/34
d.
36/j = 7/20
b.
h/36 = 21/27
e.
r/23 = 17/34
c.
26/15 = 130/m
f.
77/93 = x/24
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