Solving Proportions

Front

What is a proportion?

Back

A proportion is an equation that states that two ratios are equal. For example, if a/b = c/d, then a, b, c, and d are in proportion.

Front

How do you solve a proportion?

Back

To solve a proportion, you can use cross-multiplication. If a/b = c/d, then a*d = b*c.

Front

What is cross-multiplication?

Back

Cross-multiplication is a method used to solve proportions by multiplying the numerator of one ratio by the denominator of the other ratio.

Front

If 3/4 = x/12, what is x?

Back

x = 9. (Cross-multiply: 3*12 = 4*x, so 36 = 4x, thus x = 9.)

Front

What is the scale factor in a proportion?

Back

The scale factor is the ratio of any two corresponding lengths in two similar geometric figures.

Front

How can proportions be used in real life?

Back

Proportions can be used in various real-life situations, such as cooking (adjusting recipes), map reading (scale), and financial calculations (interest rates).

Front

What is the relationship between ratios and proportions?

Back

Ratios compare two quantities, while proportions state that two ratios are equal.

Front

If a/b = c/d, what can you say about the values of a, b, c, and d?

Back

If a/b = c/d, then the cross products are equal: a*d = b*c.

Front

What is an example of a proportion?

Back

An example of a proportion is 1/2 = 2/4, since both ratios simplify to the same value.

Front

What does it mean if two ratios are not in proportion?

Back

If two ratios are not in proportion, it means that their cross products are not equal.