A delivery company is investigating how long it takes drivers, t t\,t minutes, to complete local deliveries. They produce a table below of coded delivery times, x x\,x minutes, for a random sample of 50 deliveries.
| Coded Time (minutes) | Frequency |
|---|---|
| 0<x≤60 < x \leq 60<x≤6 | 4 |
| 6<x≤116 < x \leq 116<x≤11 | 7 |
| 11<x≤1711 < x \leq 1711<x≤17 | 24 |
| 17<x≤2617 < x \leq 2617<x≤26 | 9 |
| 26<x≤3826 < x \leq 3826<x≤38 | 6 |
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−404\displaystyle x = \frac{t - 40}{4}x=4t−40
Calculate the median and the standard deviation of ttt.
32 exam-style questions on Edexcel AS Level Maths Measures of Location and Spread, covering 2.1 Measures of Central Tendency, 2.2 Other Measures of Location, 2.3 Measures of Spread, 2.4 Variance and Standard Deviation, and 2.5 Coding. Each one has a worked solution and a mark scheme showing where the marks go.