Setting Up & Setting Proportions

Front

What is a proportion?

Back

A proportion is an equation that states that two ratios are equal.

Front

How do you set up a proportion?

Back

To set up a proportion, you can use the formula a/b = c/d, where a and b are the first ratio, and c and d are the second ratio.

Front

If 3 pounds of hamburger meat costs $6, how much does 1 pound cost?

Back

1 pound costs $2.

Front

If 18 out of 30 students have an A, what is the ratio of students with an A?

Back

The ratio is 18:30, which simplifies to 3:5.

Front

How do you find the total number of students earning an A if you know the ratio?

Back

Multiply the total number of students by the fraction of students with an A.

Front

If Pat needs 14 sticks of pepperoni for 28 pizzas, how many sticks are needed for 1 pizza?

Back

Pat needs 0.5 sticks of pepperoni for 1 pizza.

Front

What is the cross-multiplication method in proportions?

Back

Cross-multiplication involves multiplying the numerator of one ratio by the denominator of the other ratio.

Front

If a class has 25 students and 16 are boys, what is the ratio of boys to total students?

Back

The ratio is 16:25.

Front

How do you scale a ratio up or down?

Back

To scale a ratio, multiply or divide both terms of the ratio by the same number.

Front

If 14 sticks of pepperoni are needed for 28 pizzas, how many are needed for 36 pizzas?

Back

18 sticks of pepperoni are needed for 36 pizzas.