To determine the number of classes that have more than 20 and less than 27 students based on the histogram, we need to examine the bars that fall within this range.
However, you mentioned a histogram, which is a graphical representation of data using bars. Since I don't have access to the histogram you are referring to, I can't provide the exact number of classes falling within the specified range.
If you can provide the frequency or the number of bars in the histogram that correspond to the range of more than 20 and less than 27 students, I can provide you with the answer.