Now that you know how to estimate answers to problems, you are ready to learn about percentage error. The percentage error, is a percentage that tells us how far an estimate if off the actual answer. It is calculated using the error (in numerical values) and the exact answer. It is a very good way of identifying how exact your estimate was.Calculating Percentage ErrorTo calculate the percentage error you need to fin the error (the difference between your estimation and the exact answer) and the exact answer. On the right, you can see the formula used for calculating the percentage error. The vertical lines means absolute value, meaning that negative numbers become positive. The first step is to calculate the error (difference between estimation and exact answer). This is accomplished by subtracting the estimated answers from the exact answer or vice versa (it does not matter which way around as long as you ignore any - signs). Then, you divide the error which you found in the first step by the exact value which will give you a decimal. The last step is to convert the decimal into a percentage by multiplying it by 100 and adding the % sign. This gives you the percentage error. There are a few examples underneath.Continue EstimatingI hope these few lessons on estimation have helped you. You should continue developing your estimation skills as they are very important in life. Make sure to also check out some other topics on this website by visiting the library. Please share this page if you like it or found it helpful!
Example 1Estimation = 120 Exact Answer = 129In this example, we have found the error which was 9 which we then divided by the exact value before converting it into a percentage.
Example 2Estimation = 350 Exact Answer = 357.64In this example, we have found the error which was 7.64 which we then divided by the exact value before converting it into a percentage.
Example 3Estimation = 170 Exact Answer = 167.5In this example, we have found the error which was 2.5 which we then divided by the exact value before converting it into a percentage.
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Chapter 5.2: Learning OutcomesStudents will know what the percentage error shows!Students will have the ability to calculate percentage error!Students will be introduced to the concept of absolute value!