Percent Proportions Study Guide

Front

What is a percent?

Back

A percent is a ratio expressed as a fraction of 100. It represents how many parts out of 100 are being considered.

Front

How do you calculate the percentage of a number?

Back

To calculate the percentage of a number, multiply the number by the percentage (as a decimal). For example, to find 20% of 50, calculate 50 x 0.20 = 10.

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 find the total number from a percentage?

Back

To find the total number from a percentage, divide the part by the percentage (as a decimal). For example, if 24 is 80% of a number, the total is 24 / 0.80 = 30.

Front

If 18 out of 25 questions are correct, what is the percentage of correct answers?

Back

To find the percentage, divide the correct answers by the total questions and multiply by 100: (18/25) x 100 = 72%.

Front

What does it mean to find 30% of a number?

Back

Finding 30% of a number means calculating 30 parts out of 100 of that number. For example, 30% of 200 is 200 x 0.30 = 60.

Front

How do you convert a fraction to a percentage?

Back

To convert a fraction to a percentage, divide the numerator by the denominator and multiply by 100. For example, 1/4 = (1 ÷ 4) x 100 = 25%.

Front

What is the formula for finding the part when given the whole and the percentage?

Back

The formula is: Part = Whole x (Percentage as a decimal). For example, to find 20% of 50, use: Part = 50 x 0.20 = 10.

Front

If Sarah earns $20 a day and spends 30% of it, how much does she spend?

Back

To find how much Sarah spends, calculate 30% of $20: $20 x 0.30 = $6.

Front

What is the relationship between part, whole, and percentage?

Back

The relationship is defined by the formula: Percentage = (Part/Whole) x 100.