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, and x = 36/4 = 9.)

Front

What is the first step in solving the proportion 5/x = 15/20?

Back

The first step is to cross-multiply: 5*20 = 15*x.

Front

What does it mean if two ratios are equivalent?

Back

Two ratios are equivalent if they represent the same relationship between quantities, meaning they can be expressed as a proportion.

Front

How can you check if two ratios are in proportion?

Back

You can check if two ratios are in proportion by cross-multiplying and seeing if the products are equal.

Front

If a/b = c/d, what is the relationship between a, b, c, and d?

Back

The relationship is that the product of a and d equals the product of b and c (a*d = b*c).

Front

What is an example of a real-life situation that can be modeled with proportions?

Back

A real-life example is cooking: if a recipe requires 2 cups of flour for 4 servings, you can find out how much flour is needed for 10 servings using proportions.

Front

What is the term for the number that is being solved for in a proportion?

Back

The term is called the 'variable' or 'unknown'.