Probability tree and table
A school system consists of three districts, north, south, and central. The North contains 25% of the students, the south contains 40% and the central contains 35%. A minimum competency test was given to all students; 10% of the north dist. failed, 15% of the south district failed and 5% of the central failed.
a. Develop a probability tree showing all marginal, conditional, and joint probabilities.
b. Develop a joint probability table.
c. What is the probability that a student selected at random failed the test?