Would a bar graph be suitable for showing the evolution of premium? The solution shows a line graph but I was wondering if the bar graph would equivalently be suitable?
Yes - it would be suitable, but not necessarily optimal. Line graphs are best for showing how one item develops over time - there's a definite connection from one to the next. Bar graphs are better at comparing a number of different things. So while they can be used to compare premiums over time, a line graph would be better.
