pdf Finding The Interquartile Range - IQR

This worksheet provides clear, structured instruction and practice for calculating the interquartile range (IQR). Students first learn that the IQR represents the distance between the 75th percentile (Q3) and the 25th percentile (Q1), measuring the spread of the middle 50% of a data set. Step-by-step examples demonstrate how to find quartiles when a data set contains an odd number of elements and when it contains an even number of elements, including how to average two middle values when necessary.

After guided examples, students apply the process independently to multiple real-world data sets involving fish weights, quiz scores, rainfall amounts, and long jump distances. Each problem requires students to order the data, determine Q1 and Q3 correctly, and compute the IQR by subtracting \( Q_1 \) from \( Q_3 \). Because the data sets include decimals, percentages, and measurement units, students must demonstrate precision and careful organization.

This resource works well as guided practice when introducing variability, independent reinforcement during a statistics unit, or formative assessment to ensure students understand how IQR measures spread within the middle half of a distribution.

Skills Assessed

• Ordering data sets

• Determining quartiles (Q1 and Q3)

• Calculating interquartile range (IQR)

• Handling both even and odd data sets

• Interpreting variability within the middle 50% of data

• Demonstrating precision with decimals and percentages

Details

• 2 pages

• Answer key included

ID# 0384