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?

dilation scale factor 2: starting with δabc, draw the dilation image of the triangle with a center at the origin and a scale factor of two. notice that every coordinate of the original triangle has been multiplied by the scale factor (x2). dilation with scale factor 2, multiply by 2.