Of the last three chapter tests given in an astronomy class, 2 students passed all three tests, 6 students passed two tests, and 9 students passed one test. If a single student is picked at random, what is the probability that the student passed two tests or passed one test?

 Question
Of the last three chapter tests given in an astronomy class, 2 students passed all three tests, 6 students passed two tests, and 9 students passed one test. If a single student is picked at random, what is the probability that the student passed two tests or passed one test?

Provide the final answer as a fraction.

 

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