Does there appear to be a confounding variable in this situation? To determine the effectiveness of new synthetic oil, the oil is testing in 30 new Toyota Camrys (treatment group) while 30 new Honda Civics are given regular oil. Yes
No

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.

Idon’t know but you’ll figure it out