A proportion is a statement that two ratios are equal. In other words, it expresses the equality of two ratios. The general form of a proportion is:

*a/b = c/d*

Where *a, b, c,* and *d* are numbers or algebraic expressions, and *b* and *d* are not zero.

**Ratios:**A ratio is a comparison of two quantities. For example, if there are 3 boys and 5 girls in a class, the ratio of boys to girls is 3:5.**Proportional Relationships:**When two ratios are equal, they form a proportional relationship. If*a/b = c/d*, then*a*is directly proportional to*b*and*c*is directly proportional to*d*.**Cross Products Property:**In a proportion*a/b = c/d*, the cross products*ad*and*bc*are equal. This property can be used to solve proportions.

**Cross Multiplication:**To solve a proportion*a/b = c/d*, you can cross multiply by multiplying*a*by*d*and*b*by*c*. Set the resulting products equal to each other and solve for the unknown.**Equivalent Fractions:**You can also solve proportions by finding an equivalent fraction. Multiply or divide both parts of the ratio by the same number to find a new ratio that is equivalent to the given one.

Find the value of *x* in the proportion *3/5 = x/15*.

**Solution:** Using cross multiplication, we get *3 * 15 = 5x*. Simplifying, we have *45 = 5x*. Dividing both sides by 5, we find that *x = 9*.

- Understand the concept of ratios and how they are used to compare quantities.
- Learn to recognize proportional relationships and how to express them in the form of a proportion.
- Practice solving proportions using cross multiplication and finding equivalent fractions.
- Work on real-world problems that involve proportional reasoning, such as scaling and map problems.
- Review the cross products property and how it can be used to solve proportions.

Proportions are an important concept in mathematics and have many applications in everyday life. Understanding how to work with proportions will help you solve various types of problems involving comparisons and scaling.

.Study GuideOrganizing Data Worksheet/Answer key

Organizing Data Worksheet/Answer key

Organizing Data Worksheet/Answer key

Organizing Data

Data Analysis and Probability (NCTM)

Select and use appropriate statistical methods to analyze data.

Find, use, and interpret measures of center and spread, including mean and interquartile range.