Percent Proportions

Front

What is a percent?

Back

A percent is a ratio expressed as a fraction of 100. It represents how much of something exists in relation to a whole.

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 the formula for finding the total amount after tax?

Back

Total Amount = Original Price + (Original Price x Tax Rate). For example, if the original price is $80 and the tax rate is 10%, Total Amount = 80 + (80 x 0.10) = $88.

Front

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

Back

To find what percentage one number is of another, divide the first number by the second number and multiply by 100. For example, to find what percentage 3 is of 27, calculate (3/27) x 100 = 11.11%.

Front

What is 50% of a number?

Back

50% of a number is the same as dividing that number by 2. For example, 50% of 75 is 75 / 2 = 37.5.

Front

How do you calculate the percentage of a group?

Back

To calculate the percentage of a group, divide the number of items in the subgroup by the total number of items in the group and multiply by 100. For example, if 20 out of 100 students like a snack, the percentage is (20/100) x 100 = 20%.

Front

If 8 out of 10 people buy lunch, what percentage do not buy lunch?

Back

To find the percentage that do not buy lunch, subtract the percentage that do buy lunch from 100%. If 8 out of 10 buy lunch, then 2 out of 10 do not, which is (2/10) x 100 = 20%.

Front

What is the relationship between fractions and percentages?

Back

Fractions can be converted to percentages by dividing the numerator by the denominator and multiplying by 100. For example, 1/4 = (1 ÷ 4) x 100 = 25%.

Front

How do you find the total number surveyed if you know the percentage and the number in that category?

Back

To find the total surveyed, divide the number in the category by the percentage (as a decimal). For example, if 60 students like Takis and that is 20%, then Total = 60 / 0.20 = 300.

Front

What does it mean if a tax is 10%?

Back

A tax of 10% means that for every dollar spent, an additional 10 cents is added as tax. For example, if an item costs $100, the tax would be $10, making the total $110.