Final answer:
Without specific data or context, it is impossible to determine the rough percentage of users that purchase overseas; this question requires additional information typically found in a study related to population proportions and consumer behavior.
Step-by-step explanation:
The question seeks to find the rough percentage of users that purchase overseas. Without additional context, such as survey data or statistical reports, it is impossible to provide an accurate answer. However, if this information were provided as part of a study or survey and included in the dataset, then analyzing that dataset would involve calculating probabilities and identifying the correct proportion of the population engaging in overseas purchasing. Typically, such problems would be part of a probability or statistics lesson, teaching students how to work with population proportions and understand consumer behavior.