Writing and Solving Proportions

Front

What is a proportion?

Back

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

Front

How do you write a proportion?

Back

A proportion can be written as a/b = c/d, where a, b, c, and d are numbers.

Front

What is the cross-multiplication method?

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 4/3 = x/56, how do you solve for x?

Back

Cross-multiply: 4 * 56 = 3 * x, then solve for x.

Front

What is the exchange rate?

Back

An exchange rate is the value of one currency for the purpose of conversion to another.

Front

If 13 out of 20 homes have a computer, what is the ratio of homes with computers?

Back

The ratio is 13:20.

Front

How do you find the expected number of homes with computers on a street of 60 homes?

Back

Use the ratio: (13/20) * 60 = 39 homes.

Front

What is the formula to find a missing value in a proportion?

Back

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

Front

If a recipe calls for 1.5 cups of milk for every 3 cups of flour, what is the ratio of milk to flour?

Back

The ratio of milk to flour is 1.5:3 or 1:2.

Front

If Seth used 5 cups of flour instead of 3, how much milk should he use to keep the same ratio?

Back

To keep the ratio, he should use 2.5 cups of milk.