Setting Up 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 set up a proportion?

Back

To set up a proportion, identify two ratios that you want to compare and set them equal to each other. For example, if you know that 12/16 = x/18, you can solve for x.

Front

If 12 ounces of shampoo lasts 16 weeks, how long will 18 ounces last?

Back

Using proportions: 12/16 = 18/x. Cross-multiply to find x: 12x = 288, so x = 24 weeks.

Front

Pat needs 14 sticks of pepperoni for 28 pizzas. How many sticks for 36 pizzas?

Back

Set up the proportion: 14/28 = x/36. Cross-multiply to find x: 14*36 = 28x, so x = 18 sticks.

Front

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

Back

If a/b = c/x, then x = (b*c)/a.

Front

Back

Front

To make 24 ounces of hot chocolate, 6 tablespoons of cocoa are needed. How much hot chocolate can be made with 144 tablespoons?

Back

Front

How do you find the total amount from a proportion?

Back

Multiply the known ratio by the total amount and divide by the other known value. For example, if you have 14/28 = x/36, then x = (14*36)/28.

Front

What is cross-multiplication in proportions?

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 Krystal sold 56 subscriptions in 72 days, how many in 216 days?

Back

Set up the proportion: 56/72 = x/216. Cross-multiply to find x: 56*216 = 72x, so x = 168 subscriptions.