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Error Intervals

What is an Error Interval?

An error interval shows you how small or how large a rounded number could have been before it was rounded. By rounding the number we have lost some accuracy.

To write the error interval we need to find the upper bound and lower bound of the number.

The upper bound is the largest number it could have been.

The lower bound is the smallest number it could have been.

How to do an error interval

Error Interval Example Question (Edexcel Foundation June 2017, Paper 2, Question 23)

Example Question

A number, n, is rounded to 2 decimal places. 

The result is 4.76 

Using inequalities, write down the error interval for n.

A number, n, is rounded to 2 decimal places. The result is 4.76 Using inequalities, write down the error interval for n.

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