Sectieoverzicht

  • A percentage represents a fraction of 100 and is easy to identify since it is written with a percent symbol (%). Just like fractions and decimals, percentages show parts of a whole.

    Percentages can be used to quickly convey information. For example, the pie chart shows that China is the most populated country with 18.47% of the world's population.


    World population percentages  


    Before you continue with changes in percentages try the next exercise to make sure you can calculate the percentage of a number.




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      Percentage changes

      Prices of things constantly change, and one of the most common ways to describe the increase or decrease in prices is by using percentages. In fact it is often easier to get a point across about changes in numbers of anything, by using percentages.


      Percentage change in Wikimedia usage 2010 to 2021

      According to the infographic there was a 197.53% increase in usage of Wikimedia content from 2021 to 2022. But, how do we calculate percentage increase or decrease? We will go over that next. [Edit: please check dates - graphic has a mix of 2020 and 2021 and text refers to 2021 and  2022]

      Percentage increase and decrease

      We use the formula: \(\frac{New  value - original  value}{Original  value}\times 100%\) to calculate a percentage change. [Edit: the spaces between words in the formula don't show up - can this be fixed?]

      Note: A negative value in the numerator indicates percentage decrease.

      • If the new value is greater than the old value, we have a percentage increase. [Edit: old value or original value - the formula uses different terms - please check and make consistent; or explain]
      • If the new value is less than the old value, we have a percentage decrease.

      Example

      An outfit originally cost $16.25, it goes on sale for $13. What was the percentage change in price?

      Original value = $16.25

      New value = $13

      \(\frac{3.25}{16.25}\times 100%=20%\)

      The outfit costs 20% less.

      You can calculate percentage increases and decreases by using multipliers. This concept is discussed in the next video. Make sure to try the exercise that follows to test your knowledge.


    • Activity: Calculate changes in percentage Interactieve inhoud
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