Different chart styles in Numbers
Peter Shepheard I would post some screen shots here if I knew how to do it but I don't so here is a written explanation!
Select the series on your bar chart, as at the meeting, by clicking on the bar graph.
The box in the top left corner of the spread sheet changes to say Series Options.
Click the down arrow and a few options appear.
Select Line and the series you selected will change to a Line graph with the others remaining as bar graphs.
If you select the More Options you can play around in the Inspector to make other changes.
If anyone can tell me how to add screen shots I will happily do so.
Hope this helps.
Peter