High School

Name: [tex]$\qquad$[/tex]
Date: [tex]$\qquad$[/tex]
Class: [tex]$\qquad$[/tex]

**Proportion Notes**

- RATIO [tex]$=$[/tex] [tex]$\qquad$[/tex]
- RATE [tex]$=$[/tex] [tex]$\qquad$[/tex]
- UNIT RATE [tex]$=$[/tex] [tex]$\qquad$[/tex]
- PROPORTION [tex]$=$[/tex] [tex]$\qquad$[/tex]

**Proportion Examples**

1. [tex]$\frac{2}{5} = \frac{8}{20}$[/tex]
2. [tex]$\frac{400 \text{ calories }}{1 \text{ burger }} = \frac{1200 \text{ calories }}{3 \text{ burgers }}$[/tex]
3. [tex]$\frac{16}{20} = \frac{44}{55}$[/tex]

Proportions are almost always written in [tex]$\qquad$[/tex] form.

**Checking for Proportions:**

You can determine if two ratios form a proportion using two methods:

- Method 1: Simplify Both
- Method 2: Cross Products

[tex]\[
\begin{array}{l}
\frac{16}{40} \quad \div \quad - = - \\
\frac{20}{50} \quad \div \quad - = -
\end{array}
\][/tex]

So, [tex]$\frac{16}{40} \quad \frac{20}{50}$[/tex] is a [tex]$\qquad$[/tex]

[tex]$40 \cdot 20 \quad ? \quad 50 \cdot 16$[/tex]

[tex]$\qquad$[/tex] [tex]$=$[/tex] [tex]$\qquad$[/tex] [tex]$\frac{20}{50}$[/tex] is a [tex]$\qquad$[/tex]

**Checking for Proportions - Practice Problems:**

Determine whether each of the pairs of ratios forms a proportion:

a. [tex]$\frac{2}{6} \quad \frac{8}{24}$[/tex]
b. [tex]$\frac{6}{10} \quad \frac{9}{12}$[/tex]
c. [tex]$\frac{21}{30} \quad \frac{35}{50}$[/tex]
d. [tex]$\frac{1.8}{7.5} \quad \frac{1.2}{5}$[/tex]

Answer :

Sure! Let's determine whether each pair of ratios forms a proportion by using the cross-multiplication method. Cross-multiplication is a way to compare two fractions or ratios by multiplying the numerator of one ratio by the denominator of the other ratio. If the products are equal, the pairs form a proportion.

### Step-by-Step Solution:

a. Check if [tex]\(\frac{2}{6}\)[/tex] and [tex]\(\frac{8}{24}\)[/tex] form a proportion.

1. Perform cross-multiplication:
- Multiply 2 (numerator of the first ratio) by 24 (denominator of the second ratio).
- Multiply 6 (denominator of the first ratio) by 8 (numerator of the second ratio).

2. Calculate the products:
- [tex]\(2 \times 24 = 48\)[/tex]
- [tex]\(6 \times 8 = 48\)[/tex]

3. Compare the products: [tex]\(48 = 48\)[/tex]

Since the products are equal, [tex]\(\frac{2}{6}\)[/tex] and [tex]\(\frac{8}{24}\)[/tex] do form a proportion.
Result: True

---

b. Check if [tex]\(\frac{6}{10}\)[/tex] and [tex]\(\frac{9}{12}\)[/tex] form a proportion.

1. Perform cross-multiplication:
- Multiply 6 by 12.
- Multiply 10 by 9.

2. Calculate the products:
- [tex]\(6 \times 12 = 72\)[/tex]
- [tex]\(10 \times 9 = 90\)[/tex]

3. Compare the products: [tex]\(72 \neq 90\)[/tex]

Since the products are not equal, [tex]\(\frac{6}{10}\)[/tex] and [tex]\(\frac{9}{12}\)[/tex] do not form a proportion.
Result: False

---

c. Check if [tex]\(\frac{21}{30}\)[/tex] and [tex]\(\frac{35}{50}\)[/tex] form a proportion.

1. Perform cross-multiplication:
- Multiply 21 by 50.
- Multiply 30 by 35.

2. Calculate the products:
- [tex]\(21 \times 50 = 1050\)[/tex]
- [tex]\(30 \times 35 = 1050\)[/tex]

3. Compare the products: [tex]\(1050 = 1050\)[/tex]

Since the products are equal, [tex]\(\frac{21}{30}\)[/tex] and [tex]\(\frac{35}{50}\)[/tex] do form a proportion.
Result: True

---

d. Check if [tex]\(\frac{1.8}{7.5}\)[/tex] and [tex]\(\frac{1.2}{5}\)[/tex] form a proportion.

1. Perform cross-multiplication:
- Multiply 1.8 by 5.
- Multiply 7.5 by 1.2.

2. Calculate the products:
- [tex]\(1.8 \times 5 = 9.0\)[/tex]
- [tex]\(7.5 \times 1.2 = 9.0\)[/tex]

3. Compare the products: [tex]\(9.0 = 9.0\)[/tex]

Since the products are equal, [tex]\(\frac{1.8}{7.5}\)[/tex] and [tex]\(\frac{1.2}{5}\)[/tex] do form a proportion.
Result: True

I hope this helps explain whether each pair of ratios forms a proportion!