Solving Proportions

Front

What is a proportion?

Back

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

Front

How do you solve a proportion?

Back

To solve a proportion, cross-multiply the terms and then solve for the variable.

Front

If 8 sweets cost 72 cents, what is the cost of 1 sweet?

Back

9 cents.

Front

If a car travels 420 miles in 8 hours, what is its speed in miles per hour?

Back

52.5 miles per hour.

Front

What is the formula for finding a missing value in a proportion?

Back

If a/b = c/d, then ad = bc.

Front

How can you set up a proportion to solve for x in the equation 4/x = 2/8?

Back

Cross-multiply to get 4*8 = 2*x, which simplifies to x = 16.

Front

What is the relationship between the number of pizzas and sticks of pepperoni in the problem: Pat needs 14 sticks of pepperoni to make 28 pizzas?

Back

The relationship is a direct proportion; as the number of pizzas increases, the number of sticks of pepperoni increases.

Front

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

Back

18 sticks.

Front

What is the first step in solving the proportion 3/4 = x/12?

Back

Cross-multiply to get 3*12 = 4*x.

Front

How do you check if two ratios are proportional?

Back

You can check by cross-multiplying and seeing if the products are equal.