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7th Grade Math / Lesson 1: Percents

PERCENTS
What will we be learning in this lesson?


  • In this lesson, you will learn how to evaluate percents.

    Vocabulary words are found in this purple color throughout the lesson. Remember to put these in your notebook.


PERCENTS


  • Percents are used to help make comparisons. They compare quantities in terms of 100. The word "percent" actually means "per hundred".
  • There is a proportion to use when solving any type of percent problem.


  • Suppose you want to know what the percent is that you would pay for a shirt at a clothing sale. Say the original price of a shirt was  $25 but you only paid  $20. The "whole" would be the  $25 (original price of the shirt) and the "part" would be the  $20 (what you paid).
  • Let's look at how to solve this.


PERCENTS


  • First, put the numbers in where they belong.

  • Then, solve the proportion. Find the numbers on the diagonal that you know. There are two diagonals - the 20 and the 100 is one of them, and the % and the 25 is the other diagonal.

  • We will need to use the diagonal with the 20 and the 100 since we know both of the numbers. MULTIPLY these numbers together. 20 * 100 = 2000

  • Now take that answer and DIVIDE by the other number in the problem that has not been used yet. 2000 25 = 80.
    So the percent of the price that you will pay is 80% of the original price.


PERCENTS


  • Let's find another one. There are 30 students on the class roster. There are 27 students in attendance today. Find the percent of students that are here.

  • You need to figure out what you know and what you are looking for.

  • The problem says to "Find the percent..." so the percent is the number we are looking for.

  • So the other numbers are the "part" and the "whole" in the proportion.

  • Which one is which? Is 30 the "part"? Or is it the "whole"?

  • Since this is the total number of students in the class, it is the "whole" which leaves 27 as the "part".


PERCENTS


  • Now let's solve the proportion.

  • Find the diagonal of numbers that we know.


  • Multiply the numbers on this diagonal. 27 * 100 = 2700

  • Then divide by the other number that you haven't used yet.
    2700 30 = 90

    So the percent of students who are in class today is 90%


PERCENTS


    REMEMBER

  • Once you have your proportion set up, MULTIPLY the diagonal of numbers that you have, then DIVIDE by the number not used yet.


  • Can you set up the proportion to find a percent?

  • Can you solve the proportion to find a percent?

  • Be sure to go back to your classroom to get any homework assignments or other activities you need to attend to.