a graph in which classes are marked on the horizontal axis and the frequencies, percentages are marked on the vertical axis.
Note: 1.The classes or bars in a histogram are drawn adjacent to each other with no gap between them;
2. histogram is created specially for display of grouped quantitative data;
3. the most important features of the distribution of histogram are its central value, its spread, and its symmetry;
4. as a quick check, if the mean and median are approximately the same value, we can have one piece of evidence that the data may be normally distributed;
5. data is unimodal (one hump) and fairly symmetric, it appears to be close to a normal distribution.