Acertain bcd-to-decimal decoder has four input lines and 10 output lines. if four input lines are capable of 16 possible combinations and only 10 output combinations are required, why have four inputs?

You have to look at the outline

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.