Question

compare proportions from graphs & equations practice

Answer 1

To compare proportions from graphs and equations effectively, it's essential to understand the concepts behind proportions and how to analyze them visually and mathematically. Below are some key steps and examples to help you practice this skill.

### Step-by-Step Process

1. **Understanding Proportions**:
- A proportion represents a relationship between two quantities, showing how much of one exists relative to another.
- In mathematical terms, a proportion can be expressed as a fraction or ratio (e.g., \( \frac{a}{b} = \frac{c}{d} \)).

2. **Analyzing Graphs**:
- Identify the axes: Determine what the x-axis and y-axis represent.
- Look for trends: Are the values increasing, decreasing, or constant?
- Compare different sections of the graph: Notice where the proportions change.

3. **Using Equations**:
- Write down the proportions represented by the given equations.
- Solve for unknowns when necessary.
- Compare the fractions created by the equations.

4. **Cross-Multiplication**:
- When comparing two proportions (like \( \frac{a}{b} \) and \( \frac{c}{d} \)), you can cross-multiply to determine equality: \( a \cdot d = b \cdot c \).

### Example Problems

#### Example 1: Graph Analysis
Suppose you have a graph showing the number of apples and oranges sold over several months.

- **X-Axis**: Months (e.g., Jan, Feb, Mar)
- **Y-Axis**: Number of fruits sold
- **Fruit Lines**:
- Apples: A line starting at 10 in January, rising to 50 in March.
- Oranges: A line starting at 30 in January, rising to 70 in March.

**Task**:
- Calculate the proportions of apples to oranges sold in January and March.
- January: Apples = 10, Oranges = 30; Proportion = \( \frac{10}{30} = \frac{1}{3} \)
- March: Apples = 50, Oranges = 70; Proportion = \( \frac{50}{70} = \frac{5}{7} \)

#### Example 2: Equation Comparison
You have two equations representing two different scenarios:

1. \( 2x + 4 = 8 \) (Scenario A)
2. \( 3y - 1 = 11 \) (Scenario B)

**Task**:
- Solve for \( x \) and \( y \):
- From Scenario A: \( 2x + 4 = 8 \)
- \( 2x = 4 \)
- \( x = 2 \)

- From Scenario B: \( 3y - 1 = 11 \)
- \( 3y = 12 \)
- \( y = 4 \)

- Compare Proportions:
- Proportion of A to B: \( \frac{x}{y} = \frac{2}{4} = \frac{1}{2} \)

### Practice Problems
1. Examine the following scenario with a graph and write the proportions observed.
- Graph of bicycles and scooters sold over a week.

2. Given the equations:
- \( 4a + 2 = 18 \)
- \( 5b - 5 = 10 \)
- Solve for \( a \) and \( b \), then compare the proportions of \( a \) to \( b \).

### Tips
- Always check your calculations for errors.
- Practice interpreting different types of graphs (e.g., bar graphs, line graphs).
- Familiarize yourself with how to manipulate equations for solving proportions.

By regularly practicing these concepts, you will become proficient in comparing proportions from both graphical and mathematical perspectives.