Is y=0.3x proportional or non proportional?

Proportional
The graph is linear since it goes up by the same rate each time, and the line crosses the point of origin.

The major difference is that a histogram is only used to plot the frequency of score occurrences in a continuous data set that has been divided into classes, called bins.  bar charts, on the other hand, can be used for a great deal of other types ofvariables  including  ordinal  andnominal  data sets.