Before 1995, three-digit area codes for the united states had the following restrictions:
(a) neither 0 nor 1 could be used as the first digit.
(b) 0 or 1 had to be used for the second digit.
(c) there were no restrictions on the third digit.
how many different area codes were possible?

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.