A company is investigating how long it takes employees, t t\,t minutes, to get to an event. They produce a table below of coded times, x x\,x minutes, for a random sample of 50 employees.
| Coded Time (minutes) | Frequency |
|---|---|
| 0<x≤50 < x \leq 50<x≤5 | 1 |
| 5<x≤105 < x \leq 105<x≤10 | 9 |
| 10<x≤1510 < x \leq 1510<x≤15 | 19 |
| 15<x≤2515 < x \leq 2515<x≤25 | 14 |
| 25<x≤4025 < x \leq 4025<x≤40 | 7 |
Use linear interpolation to estimate the median of the coded times.
Estimate the standard deviation of the coded times.
The coded data was calculated using the formula: x=t−202\displaystyle x = \frac{t - 20}{2}x=2t−20
Calculate the median and the standard deviation of ttt.
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.