Pre-Algebra interquartile range worksheet
Order the data and find the median. Q1 is the median of the lower half and Q3 the median of the upper half, the middle value itself left out of both when the count is odd. The interquartile range is Q3 minus Q1: how wide the middle half of the data is, which outliers cannot stretch.
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Sigma Prep · sigmaprep.io/worksheets Name Interquartile RangeDate Period Find the interquartile range of each set.
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Sigma Prep · sigmaprep.io/worksheets Name Interquartile RangeAnswer keyVersion 1Date Period Find the interquartile range of each set.
Free math worksheets at sigmaprep.io/worksheets© 2026 Sigma Prep |
How to do these
Find the interquartile range:
- The median is 7. The lower half is 3, 4, 5 and the upper half 10, 10, 10.
- Q1 = 4 and Q3 = 10.
The answer is .
Where students go wrong
Including the median in both halves when the count is odd. It belongs to neither, and the quartiles move if it is counted.
Also called IQR, quartiles, Q1 and Q3 or measures of spread.