<image> After the preliminary test of the mathematics competition for the third year of high school in a certain school, the scores above 90 points (including 90 points) were counted, and their frequency distribution histogram is as shown in the figure. If the number of people in the 130-140 score range is 2.
(1) Estimate the number of students from this school who participated in the competition with scores between 90 and 140;
(2) Estimate the median score of the participating students;
(3) Now, based on the preliminary test scores, two people are randomly selected from the first group and the fifth group (the first group, the second group, ..., the fifth group, sequentially from the low-score section to the high-score section), and they form a study help group. If the score difference between the two selected people is greater than 20, then they are called a "golden partner group". Calculate the probability that the two selected people form a "golden partner group".