Question

define frequency of an observation in a bar graph

Answer 1

It gives information about number of people or anything.

Answer 2

A bar chart is a type of graph in which each column (plotted either vertically or horizontally) represents a categorical variable or a discrete ungrouped numeric variable. 

It is used to compare the frequency (count) for a category or characteristic with another category or characteristic.

Features of a bar chart:In a bar chart, the bar height (if vertical) or length (if horizontal) shows the frequency for each category or characteristic.The distribution of the dataset is not important because the columns each represent an individual category or characteristic rather than intervals for a continuous measurement. Therefore, gaps are included between each bar and each bar can be arranged in any order without affecting the data.

i know  this much