Final answer:
Susan is uncovering a type of data variable classified as numeric data, which is quantitative and can be used for statistical analysis in fundraising efforts.
Step-by-step explanation:
In the scenario given, Susan is attempting to uncover a type of data variable by targeting individuals who were born between 1920 and 1980 in the alumni database for the purpose of a fundraising campaign to renovate their Gymnasium. Based on the context provided, Susan is interested in the birth years of the alumni, which can be classified as numeric data. Numeric data is quantitative and can be measured and ordered, making it ideal for statistical analysis that could assist Susan in segmenting her database for targeted fundraising efforts.