About this video
Mateo predicts 24 cookies but makes 20. Percent error is the error divided by the actual amount: (24 − 20) ÷ 20 = 4/20 = 0.2 = 20%.
You'll be able to
- find the error as the difference between an estimate and the actual value.
- calculate percent error as error divided by actual, times 100%.
Key words
- Percent error
- How far off an estimate is, as a percent of the actual value.
- Overestimate
- A guess that is bigger than the actual amount.
- Actual
- The true or real amount, here the 20 cookies Mateo made.
Transcript
- [Narrator] Mateo predicts his cookie dough will make 24 cookies. He is actually able to make 20 cookies. What is the percent error of Mateo's estimate? Pause this video, have a go at that. Alright, so when we're talking about percent error, you could think of it as error over actual.
And assuming your error is, well, actually sometimes your error isn't smaller than your actual, but in many cases your error will be smaller than your actual and this will give you some decimal value between zero and one. If you want to express it as a percentage of course, you can multiply it by 100% and of course, 100% is just equal to one.
But let's do it in this situation. In this situation, our error, we thought we were gonna get 24, which is an overestimate, minus the actual, which is 20, actually able to make 20 cookies. And then the actual I just said is 20. And of course, we can multiply that times 100%.
This is going to be equal to 4 over 20, which is 0.2. You multiply that times 100%, of course, that would get us to a 20% error.
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