Basic Concepts
In a nutshell: Ratios, rates, and proportions help us compare and scale quantities.
## Comparing Quantities
Ratios compare two quantities, like 3 apples to 4 oranges (written as 3:4). Rates compare quantities with different units, like 60 miles per 2 hours.
### Proportions
If two ratios are equal, they form a proportion: \( \frac{3}{4} = \frac{6}{8} \).
### Solving Proportional Problems
Cross-multiply to solve: If \( \frac{5}{8} = \frac{x}{24} \), then \( 5 \times 24 = 8 \times x \), so \( x = 15 \).
### Daily Life Connections
Proportions help when cooking, shopping, or planning trips.
### Fun Example
If 2 pencils cost $1, how much do 10 pencils cost? Set up a proportion to find out!
Examples
- A recipe calls for 2 cups of flour for every 3 cups of sugar.
- If you bike 20 miles in 2 hours, your rate is 10 miles per hour.