This study involved the use of "economic reasoning," which refers to the application of the concept of cost-benefit analysis to personal decision making. The study examined the degree of economic reasoning employed by high school seniors who had received instruction in cost benefit analysis. The main purpose of the study was to compare the economic reasoning used by a group of students that was faced with a realistic, non-hypothetical decision about how to allocate their time with the economic reasoning used by a group of students that was faced with a hypothetical decision about how they would allocate their time. Specifically, the non-hypothetical dilemma faced by the first group of students was deciding what to do during a "free" half class period, while the hypothetical dilemma faced by the second group of students was reporting what they would do if given a "free" half class period. The results of the study suggested that students facing hypothetical time allocation dilemmas employ as much economic reasoning as students facing non-hypothetical dilemmas. A 6-item list of references is included. (DB)