Answer to Question 1
A histogram is used to convey the distribution of a quantitative variable. The horizontal axis represents the range of possible values for the variable of interest. The bars are joined together to form the distribution. A bar chart is used to illustrate a qualitative variable. By using gaps between the bars, the differences between the categories are more easily seen.
Answer to Question 2
A line chart is used to display data that are measured in sequence over time. The points are in a defined order. Connecting the points serves to illustrate any trend that may be present in the data. A scatter plot is used to show the relationship between two variables. The XY data points are plotted in a two-dimensional space. The order that the XY points are recorded is of no consequence, so connecting the points would be meaningless.
