Percent Proportions

Front

What is a percent?

Back

A percent is a way of expressing a number as a fraction of 100. It is denoted by the symbol '%'. For example, 50% means 50 out of 100.

Front

How do you calculate the percent of a number?

Back

To calculate the percent of a number, multiply the number by the percent (in decimal form). For example, to find 20% of 50, calculate 50 * 0.20 = 10.

Front

What is the formula to find the total amount when given a percent and a part?

Back

The formula is: Total = Part / (Percent / 100). For example, if 30 is 20% of a total, the total is 30 / (20 / 100) = 150.

Front

How do you find what percent one number is of another?

Back

To find what percent one number (part) is of another number (whole), use the formula: (Part / Whole) * 100. For example, to find what percent 25 is of 200, calculate (25 / 200) * 100 = 12.5%.

Front

What is a proportion?

Back

A proportion is an equation that states that two ratios are equal. For example, if a/b = c/d, then a, b, c, and d are in proportion.

Front

How do you set up a proportion to solve for an unknown?

Back

To set up a proportion, write the known ratios as fractions and set them equal to each other. For example, if x is unknown in the proportion 1/2 = x/8, cross-multiply to solve: 1*8 = 2*x.

Front

What is the relationship between fractions and percents?

Back

Fractions and percents are two ways to represent the same concept. To convert a fraction to a percent, divide the numerator by the denominator and multiply by 100.

Front

How do you convert a percent to a decimal?

Back

To convert a percent to a decimal, divide the percent by 100. For example, 75% as a decimal is 75 / 100 = 0.75.

Front

What is 25% of 200?

Back

25% of 200 is 50. (200 * 0.25 = 50)

Front

If 40% of a number is 80, what is the number?

Back

The number is 200. (80 / 0.40 = 200)