IDX Some students were playing tag on a
playground. The number of girls was
three less than twice the number of boys.
If there were 7 girls, how many boys were
playing tag?
Write an equation?

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.