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# Percentage errors watch

1. My teacher told us that to work out percentage errors, you use the formula: smallest division x 100
-------------------
measurement of volume

But I have also been told that you work out percentage error by using this formula:

maximum error x 100
--------------
measurement of volume

When you use the maximum error method, it gives you half of the percentage error of the result you obtained from the first formula because to work out maximum error you have to halve the smallest division that is on any equipment.

Any help? Confused...which method is the correct one?
2. (Original post by Gagannn_)
My teacher told us that to work out percentage errors, you use the formula: smallest division x 100
-------------------
measurement of volume

But I have also been told that you work out percentage error by using this formula:

maximum error x 100
--------------
measurement of volume

When you use the maximum error method, it gives you half of the percentage error of the result you obtained from the first formula because to work out maximum error you have to halve the smallest division that is on any equipment.

Any help? Confused...which method is the correct one?
Both methods are used, however you should use your judgement according to the situation.

The best approach is to use the degree of doubt or inaccuracy in a specific measurement.

For example a 2 dp electronic balance recording one mass of 5.00g has an inaccuracy of ±0.005 making the percentage error 0.005/5 x 100 = 0.1% error

However in a titration you have to take two readings and each one must be assessed for accuracy. If you decide that you are capable of reading the burette with an uncertainty of ±0.05 ml then after two such readings your inaccuracy is 2 x 0.05 ml = 0.1 ml and the percentage error in a titre of 25 ml = 0.1/25 x 100 = 0.4%

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