We can also assign groups through the fill argument. This has the added benefit that it uses colors to distinguish the groups, like this: However, here the second density is drawn over the other. We...

We can also assign groups through the fill argument. This has the added benefit that it uses colors to distinguish the groups, like this:

However, here the second density is drawn over the other. We can make the curves more visible by using alpha blending to add transparency. Set the alpha parameter to 0.2 in the geom_density function to make this change.