The most likely income will be the one with the highest frequency density, being between 80 and 100 thousand.

Thx for the guide but I'm still quite confused over the frequency density part. What is that? Is that really necessary to plot a histogram? :)

Frequency density shows how closely packed the 'stuff' within a class really is. This is useful as it truly shows how the frequency is distributed across the classes in a histogram.

Say, hypothetically: there are 100 families earning between 0 and 100 thousand dollars a year. There are also 20 families earning between 100 and 110 thousand dollars. Even though there are fewer families in the second class, it is more common. This is because there is a higher density of families within it.

A histogram is unique because at a glance it shows the most common and least common classes, because of the frequency density. It is not a histogram if there is no frequency density on the y axis.

By definition, the frequency density is the number of occurrences per unit of class width.

Thx a lot for the help. I get it now