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360 Soving Percent Problems Using Proportions

How to set up proportions to solve percent problems

calculator, paper and pencil

Remember that percent originally meant "cent", or if you prefer, "part(s) out of 100." If we keep this in mind, it's a lot easier to set up a proportion. In fact we always use the same label of
when we set ours up.

Let's take a look at a few:

  1. What is 30% of $35.
    This means, how much out of 35 would be equivalent to 30 parts out of 100? The proportion will look like this:
    Remember the products of the diagonal numbers are equal in any proportion.
  2. 38 is what percent of 600?
    This means, 38 out of 600 is equivalent to how many parts out of 100?
    You might want to reduce the percent fraction if you don't have a calc. It will make the computation easier.
  3. 8 is 60% of what number?
    This means, 60 parts out of 100 parts is equivalent to 8 parts out of how many. Here we are searching for the "whole" of which 8 is the top "part."
    You might want to reduce the percent fraction if you don't have a calc. It will make the computation easier.

  1. Find 40% of 50. (answer)
  2. 2 is what % of 100? (answer)
  3. What percent of 80 is 60? (answer)
  4. 27 is 60% of what number? (answer)

Things to consider when teaching this lesson


340 The History of Percent

350 Converting Percents to Decimals and Fractions


370 Using Equations to Solve Percent Problems

The Customizable Percent Test

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