Tablas estadísticas

A histogram is a graph that displays the classes on the horizontal axis and the frequencies of the classes on the vertical axis. The frequency of each class is represented by a vertical bar whose height is equal to the frequency of the class (when all the class widths are equal).

The exam scores of a group of students are given by the following table:

Score	0-19	20-39	40-59	60-79	80-99
Frequency	5	4	6	2	1

Construct the histogram.

A histogram is similar to a bar graph. However bar charts are not appropiate for data with grouped frequencies for ranges of values, instead we use a histogram which is a diagram in which rectangles are used to represent frequencies. A histogram differs from the bar chart in that the rectangles may have different widths, but the key feature is that, for each rectangle area is proportional to class frequency.