Proportions and Percents

Front

What is a proportion?

Back

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

Front

How do you find a percentage of a number?

Back

To find a percentage of a number, multiply the number by the percentage (in decimal form). For example, to find 30% of 200, calculate 200 x 0.30 = 60.

Front

What is 50% of a number?

Back

50% of a number is half of that number. For example, 50% of 100 is 50.

Front

What does it mean for two ratios to be proportional?

Back

Two ratios are proportional if they can be expressed as equivalent fractions.

Front

How do you convert a fraction to a percent?

Back

To convert a fraction to a percent, divide the numerator by the denominator and then multiply by 100. For example, 1/4 = 0.25 x 100 = 25%.

Front

What is the formula to calculate the percent increase?

Back

Percent Increase = ((New Value - Original Value) / Original Value) x 100.

Front

If 40% of a class of 30 students are girls, how many girls are in the class?

Back

12 girls (40% of 30 = 0.40 x 30 = 12).

Front

What is the relationship between ratios and proportions?

Back

Ratios compare two quantities, while proportions show that two ratios are equal.

Front

How do you find the total amount if you know the part and the percentage?

Back

Total Amount = Part / (Percentage in decimal form). For example, if 30 is 25% of a total, Total = 30 / 0.25 = 120.

Front

What is 25% of 80?

Back

20 (25% of 80 = 0.25 x 80 = 20).