A car dealership sells both new and used cars. The number of new cars sold on a given day ranges from 5 to 30 while the number of used cars sold ranges from 5 to 40. The number of used cars sold is mutually exclusive to the number of new cars sold. Which statistic would be used to compare the number of new and used car sales on any given day?

R-squared is a statistical measure used primarily in regression analysis to indicate the proportion of variance in the dependent variable that can be explained by the independent variable(s). It is not suitable for comparing counts of mutually exclusive categories like new and used car sales.

A Z-score indicates how many standard deviations an element is from the mean of a dataset. While useful for understanding the relative position of values within a single dataset, it does not apply to the comparison of two distinct categories of sales data, such as new versus used cars.

The Chi-square test evaluates whether the observed frequencies of categories differ significantly from expected frequencies under the null hypothesis. This makes it the correct choice for analyzing and comparing the sales data of new and used cars, as it directly addresses the relationship between these two mutually exclusive categories.