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 12 pictures take 5 minutes, how do you find the time for 132 pictures?

Back

Set up the proportion: 12/5 = 132/x, then cross-multiply and solve for x.

Front

What is the unit rate?

Back

The unit rate is a comparison of any two units, expressed as a quantity of one unit.

Front

How do you find the cost per apple if 50 apples cost $25.00?

Back

Divide the total cost by the number of apples: $25.00 / 50 apples = $0.50 per apple.

Front

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

Back

Speed = distance/time, so 120 miles / 3 hours = 40 miles per hour.

Front

How do you determine how many boxes Nathan can pack in 8 hours?

Back

First, find the rate: 39 boxes / 3 hours = 13 boxes per hour. Then multiply by 8 hours: 13 * 8 = 104 boxes.

Front

What is the relationship between the size of the shampoo bottle and its duration of use?

Back

Larger bottles last longer; if a 12-ounce bottle lasts 16 weeks, an 18-ounce bottle will last proportionally longer.

Front

How do you set up a proportion to find the cost of 75 apples?

Back

Set up the proportion: 50 apples/$25 = 75 apples/x, then cross-multiply and solve for x.

Front

What does cross-multiplication mean in solving proportions?

Back

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