Range, Quartiles & The Interquartile Range (IQR)

Practice range, quartiles & the interquartile range (iqr) through 20 original single-select and multiselect questions. Build from core understanding and calculations to interpretation, counterexamples and method selection. Prerequisites: arithmetic, percentages, ordered data and the preceding foundations topics. Calculate total and central spread; Use explicit quartile conventions; Interpret five-number summaries; Calculate inner fences and modified whiskers; Analyze scale changes and tied data; Distinguish outlier flags from errors. Worked solutions explain the reasoning and each distractor. Quantile, trimming and variance conventions are stated where needed. Sources include NIST and established statistical documentation. Cover photograph: Lukas Blazek / Pexels.