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 solve a proportion?

Back

To solve a proportion, cross-multiply the two ratios and set the products equal to each other.

Front

If 4 pages take 18 minutes to read, how do you find the time to read 30 pages?

Back

Set up the proportion: 4 pages/18 minutes = 30 pages/x minutes, then cross-multiply and solve for x.

Front

What is the unit rate?

Back

The unit rate is a comparison of two different quantities when they are combined together, expressed as a quantity per one unit.

Front

How do you find the unit rate of speed?

Back

To find the unit rate of speed, divide the total distance traveled by the total time taken.

Front

If a car travels 120 miles in 3 hours, what is its speed in miles per hour?

Back

Speed = Distance/Time = 120 miles/3 hours = 40 miles per hour.

Front

How do you set up a proportion for a word problem?

Back

Identify the two ratios in the problem, then set them equal to each other.

Front

What is the cost per slice of pizza if a pizza with 8 slices costs $12?

Back

Cost per slice = Total cost/Number of slices = $12/8 slices = $1.50 per slice.

Front

If there are 5 ice cream cones for every 3 brownies, how do you find the number of cones sold if 24 brownies were sold?

Back

Set up the proportion: 5 cones/3 brownies = x cones/24 brownies, then cross-multiply and solve for x.

Front

What is cross-multiplication in proportions?

Back

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