Variance & Standard Deviation

Practice variance & standard deviation through 30 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. Separate signed, absolute and squared deviations; Distinguish population and sample dispersion; Calculate variance and standard deviation; Explain degrees of freedom and correction assumptions; Analyze affine transformations of spread; Diagnose computational and summary-information pitfalls. 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.