Two samples of delivery times are summarised below.
| Sample | Size | Median (minutes) | Interquartile range (minutes) | Mean (minutes) | Standard deviation (minutes) |
|---|---|---|---|---|---|
| A | 40 | 28 | 6 | 31.4 | 12.8 |
| B | 60 | 30 | 10 | 30.8 | 7.2 |
In this question you must show detailed reasoning.
Compare the location and spread of the two samples.
Suggest what the differences between the mean and median indicate about Sample A.
Explain why the summaries are not enough to decide whether either sample contains an outlier under the 1.5×IQR1.5\times\mathrm{IQR}1.5×IQR rule.
121 exam-style questions on OCR A Level Maths 2.2 Data Presentation and Interpretation, covering 2.2.1 Tables and diagrams for single variable data, 2.2.2 Area in a histogram, 2.2.3 Scatter diagrams and regression lines, 2.2.4 Informal interpretation of correlation, 2.2.5 Correlation and causation, 2.2.6 Measures of average and spread, 2.2.7 Calculations of mean and standard deviation, 2.2.8 Outliers, 2.2.9 Selecting or critiquing data presentation, and 2.2.10 Cleaning data. Each one has a worked solution and a mark scheme showing where the marks go.