Question: A metropolitan school system consists of three districts north, south, and central. The north district contains 25 percent of all students, the south district contains 40 percent, and the central district contains 35 percent. A minimum-competency test was given to all students; 10 percent of the north district students failed, 15 percent of the south district students failed, and 5 percent of the central district students failed. Create a joint probability table.