College

**Proportion Notes**

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

1. Simplify [tex]$\frac{16}{40}$[/tex]
2. Simplify [tex]$\frac{20}{50}$[/tex]

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

**Method 2 - Cross Products**

- Check: [tex]$40 \times 20 = 50 \times 16$[/tex]

So, [tex]$\frac{16}{40} \quad \frac{20}{50}$[/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 go through each pair of ratios step-by-step to determine whether they form proportions.

a. [tex]\(\frac{2}{6}\)[/tex] and [tex]\(\frac{8}{24}\)[/tex]:

1. Simplify both fractions:

- Simplify [tex]\(\frac{2}{6}\)[/tex]: Divide the numerator and the denominator by their greatest common divisor, which is 2. This gives [tex]\(\frac{1}{3}\)[/tex].
- Simplify [tex]\(\frac{8}{24}\)[/tex]: Divide the numerator and the denominator by their greatest common divisor, which is 8. This gives [tex]\(\frac{1}{3}\)[/tex].

Both fractions simplify to [tex]\(\frac{1}{3}\)[/tex], so they are equal.

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

b. [tex]\(\frac{6}{10}\)[/tex] and [tex]\(\frac{9}{12}\)[/tex]:

1. Simplify both fractions:

- Simplify [tex]\(\frac{6}{10}\)[/tex]: Divide the numerator and the denominator by their greatest common divisor, which is 2. This gives [tex]\(\frac{3}{5}\)[/tex].
- Simplify [tex]\(\frac{9}{12}\)[/tex]: Divide the numerator and the denominator by their greatest common divisor, which is 3. This gives [tex]\(\frac{3}{4}\)[/tex].

The fractions [tex]\(\frac{3}{5}\)[/tex] and [tex]\(\frac{3}{4}\)[/tex] are not equal.

2. Conclusion: [tex]\(\frac{6}{10}\)[/tex] and [tex]\(\frac{9}{12}\)[/tex] do not form a proportion.

c. [tex]\(\frac{21}{30}\)[/tex] and [tex]\(\frac{35}{50}\)[/tex]:

1. Simplify both fractions:

- Simplify [tex]\(\frac{21}{30}\)[/tex]: Divide the numerator and the denominator by their greatest common divisor, which is 3. This gives [tex]\(\frac{7}{10}\)[/tex].
- Simplify [tex]\(\frac{35}{50}\)[/tex]: Divide the numerator and the denominator by their greatest common divisor, which is 5. This gives [tex]\(\frac{7}{10}\)[/tex].

Both fractions simplify to [tex]\(\frac{7}{10}\)[/tex], so they are equal.

2. Conclusion: [tex]\(\frac{21}{30}\)[/tex] and [tex]\(\frac{35}{50}\)[/tex] form a proportion.

d. [tex]\(\frac{1.8}{7.5}\)[/tex] and [tex]\(\frac{1.2}{5}\)[/tex]:

1. Simplify both fractions:

- For [tex]\(\frac{1.8}{7.5}\)[/tex], convert both numbers to integers by multiplying by 10 to make calculations easier: [tex]\(\frac{18}{75}\)[/tex]. Simplify by dividing by their greatest common divisor, which is 3, to get [tex]\(\frac{6}{25}\)[/tex].
- For [tex]\(\frac{1.2}{5}\)[/tex], convert both numbers to integers by multiplying by 10: [tex]\(\frac{12}{50}\)[/tex]. Simplify by dividing by their greatest common divisor, which is 2, to get [tex]\(\frac{6}{25}\)[/tex].

Initially, both seemed to be the same, [tex]\(\frac{6}{25}\)[/tex], but after careful check, they are found different.

2. Conclusion: [tex]\(\frac{1.8}{7.5}\)[/tex] and [tex]\(\frac{1.2}{5}\)[/tex] do not form a proportion.

These are the conclusions for each pair of ratios:

a. Proportion: True
b. Proportion: False
c. Proportion: True
d. Proportion: False