Two machines fill packets. The packet masses have the following summaries.
| Machine | Mean mass (g) | Standard deviation (g) |
|---|---|---|
| A | 500 | 4.2 |
| B | 497 | 7.1 |
State which machine fills packets with the greater average mass.
State which machine is more consistent. Give a reason.
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.