5 The diameters of 100 pebbles were measured. The measurements rounded to the nearest millimetre, \(x\), are summarised in the table.
| \(x\) | \(10 \leqslant x \leqslant 19\) | \(20 \leqslant x \leqslant 24\) | \(25 \leqslant x \leqslant 29\) | \(30 \leqslant x \leqslant 49\) |
| Number of stones | 25 | 22 | 29 | 24 |
These data are to be presented on a statistical diagram.
- For a histogram, find the frequency density of the \(10 \leqslant x \leqslant 19\) class.
- For a cumulative frequency graph, state the coordinates of the first two points that should be plotted.
- Why is it not possible to draw an exact box-and-whisker plot to illustrate the data?