Topics › Statistics › Margin of Error — Confidence Interval Width
Statistics · COL

Margin of Error — Confidence Interval Width

Margin of error = z* · (σ/√n) for means; z* · √(p̂(1−p̂)/n) for proportions. 95% CI uses z* ≈ 1.96.

StatisticsCommon Core UNC-4.BCOLVerified correct ✓

Worked examples

A 95% confidence interval is being constructed for a population mean. The population standard deviation is σ = 5 and the sample size is n = 49. Calculate the margin of error. (Use z* = 1.96 for 95%.)
Answer: 1.4
A 90% confidence interval is being constructed for a population mean. The population standard deviation is σ = 5 and the sample size is n = 64. Calculate the margin of error. (Use z* = 1.645 for 90%.)
Answer: 1.0281

Every problem on Pounce is generated and checked by code — never a wrong answer key.

Master Margin of Error — Confidence Interval Width

Code-verified problems at exactly the right level, explained the way your kid learns.

Start your free trial 🐾

Build up to this

Normal Probability Calculations Using z-tablesMean and Standard Deviation — Compute and Interpret

More Statistics topics

Frequency Tables — Relative Frequency and Marginal DistributionsCompare Distributions — Shape, Center, Spread, and Outliers (SOCS)Dot Plots and Histograms — Construct and InterpretBoxplots and the Five-Number SummaryMean and Standard Deviation — Compute and InterpretStandardized Scores (z-scores) — Position Within a DistributionNormal Distribution — The 68-95-99.7 Empirical RuleNormal Probability Calculations Using z-tables