Percentages and Percent Composition

Created by The North Carolina School of Science and Math. Copyright 2012. North Carolina Department of Public Instruction.

Percentages

Percent

Percentages

Examples?

30%0.5%120%

Number of People who Like This Team

Duke = 50 Carolina = 30NC State = 20 Other = 5

Percentages: Basic Equation

• A basic equation to help you solve problems with percentages:

Percentage = () x 100

Percentages: Types of Problems

What you Know What you are Trying to Find

Whole and Part PercentageWhole and Percentage

Part

Percentage and Part

Whole

Percentages: Examples

You are testing a airplane wing design in a wind tunnel. You complete 20 trials total. Only 15 of these trials were successful. What percentage of trials were successful?

Percentages: Examples

You are studying a specific metal alloy. You know that 10% of the alloy is made of steel. If you have a 50 gram sample of this material, how much of the material is steel?

Percentages: Examples

You have spent $120.00 on various materials for the prototype which you are designing. You know this is 80% of your design budget. What is your total budget?

Percent Composition

In Material Science…• Percent Composition is used to determine the

amount of each element in a compound

Why should Engineers care about this?