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 terms and then solve for the unknown variable.

Front

What does it mean to cross-multiply?

Back

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

Front

If 3/4 = x/12, what is x?

Back

x = 9 (Cross-multiply: 3 * 12 = 4 * x) => 36 = 4x => x = 9.

Front

What is the formula for finding a percentage?

Back

Percentage = (Part/Whole) * 100.

Front

If you made 75% of your attempts, how do you find the number of successful attempts?

Back

Multiply the total attempts by the percentage (in decimal form). For example, 12 attempts * 0.75 = 9 successful attempts.

Front

What is the unit rate?

Back

The unit rate is a comparison of any two measurements in which the second term is 1.

Front

If Alice earned $20.40 in 3 hours, how do you find her hourly rate?

Back

Divide the total earnings by the number of hours: $20.40 / 3 hours = $6.80 per hour.

Front

How do you set up a proportion to find an unknown height using shadows?

Back

Set up the proportion as: height of person / length of person's shadow = height of statue / length of statue's shadow.

Front

If a 6-foot person casts a 2-foot shadow, what is the height of a statue that casts a 10-foot shadow?

Back

Height of statue = (6 feet / 2 feet) * 10 feet = 30 feet.