A company is investigating how long it takes employees, t t\,t minutes, to get to an event. The table below gives the coded times, x x\,x minutes, for a random sample of 50 employees.
| Coded time (minutes) | Frequency |
|---|---|
| 0<x≤50 < x \le 50<x≤5 | 1 |
| 5<x≤105 < x \le 105<x≤10 | 9 |
| 10<x≤1510 < x \le 1510<x≤15 | 19 |
| 15<x≤2515 < x \le 2515<x≤25 | 14 |
| 25<x≤4025 < x \le 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 times were obtained using x=t−202\displaystyle x = \frac{t - 20}{2}x=2t−20. Estimate the median and the standard deviation of ttt.
39 exam-style questions on AQA A Level Maths 2.2.3 Central tendency, variation and standard deviation. Each one has a worked solution and a mark scheme showing where the marks go.