Percentage and Proportions Problems

Front

What is a percentage?

Back

A percentage is a way of expressing a number as a fraction of 100. It is often used to compare proportions.

Front

How do you calculate a percentage of a number?

Back

To calculate a percentage of a number, multiply the number by the percentage (in decimal form). For example, to find 30% of 900, calculate 900 * 0.30 = 270.

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 convert a fraction to a percentage?

Back

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

Front

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

Back

The formula is: Total = Part / (Percentage in decimal form). For example, if 45% of customers rated a shop as satisfactory and 108 customers did, Total = 108 / 0.45 = 240.

Front

If 80% of a number is 96, how do you find the original number?

Back

To find the original number, divide the part by the percentage in decimal form: Original Number = 96 / 0.80 = 120.

Front

What does it mean if a student answered 85% of questions correctly?

Back

It means the student got 85 out of every 100 questions correct. If there were 40 questions total, the student answered 34 correctly.

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 108 is of 240, calculate (108 / 240) * 100 = 45%.

Front

What is the relationship between percentages and fractions?

Back

Percentages can be expressed as fractions by placing the percentage over 100. For example, 25% = 25/100 = 1/4.

Front

How can you estimate a percentage?

Back

To estimate a percentage, round the numbers to make calculations easier. For example, to estimate 60% of 365, round to 360 and calculate 60% of 360 = 216.