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Using a Percent Model

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Using a Percent Model

Pre-Algebra

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Use a percent model to explain how percents can be used to solve problems that involve percents.

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Now You Know

After completing this tutorial, you will be able to complete the following:

  • Use a percent model to calculate the part given the percent and base.
  • Use a percent model to calculate the percent given the part and base.
  • Use a percent model to calculate the base given the part and percent.
  • Use a percent model to solve real-world problems.

Everything You'll Have Covered

A percent is a part of one hundred.

A percent is a ratio in which the whole is 100, so percent means "out of 100." We can show a percent using a model such as a percent ruler.

Example:

We can use the above percent model to solve problems involving percents.

The model is divided into equal parts, with the units at the bottom of the model representing the percent and the units at the top representing the number of parts of the whole. The last part is the whole part.

Using percent proportion to solve problems involving percent

We can also use percent proportion to figure out the part, base or percent. In percent proportion, one ratio compares part of a quantity to the whole quantity, which is called the base. The other ratio is a fraction whose numerator is the percent and denominator is 100.

To figure out a, b or p in this proportion, we just need to put the given information into the proportion and then solve it using the cross-product property.

In this Activity Object, problems are also solved using percent proportion, but the main focus is on using the percent model. There is a separate Activity Object called "Use Percent Proportion to Solve Problems" which demonstrates this alternate method.

Let's see how to find the part using percent proportion:

Problem: Find 40% of 600.
Part = x
Whole = 600
Percent = 40

Two other ways to find the part:

  1. The percent can be converted into a decimal and then multiplied by the whole.
    40% = 0.4
    0.4 of 600 = 0.4 600
    = 240
  2. The percent can be converted into a fraction and then multiplied by the whole.
    40% =

Tutorial Details

Approximate Time 15 Minutes
Pre-requisite Concepts cross products, operations on whole numbers, percents, proportions
Course Pre-Algebra
Type of Tutorial Skills Application
Key Vocabulary percent, percent model, percent proportion