A school district performed a study to find the main causes leading to its students dropping out of school. Thirty cases were analyzed, and a primary cause was assigned to each case. The causes included unexcused absences (U), illness (I), family problems (F), and other causes (O). The results for the thirty cases are listed below: U U U I F O O U I F F O U I I F I I O U I F F U U I I O F U

Required:
Construct a table summarizing the frequency distribution of the primary causes leading to student dropout.