<image>In the ninth grade of a certain school, 200 students participated in the preliminary round of the National Junior High School Mathematics Competition. To understand the performance in this preliminary round, 50 students were sampled, and their preliminary scores were analyzed to obtain the frequency distribution histogram shown in the . Observe the information in the graph and answer the following questions:
(1) The frequency of the fourth group is ______.
(2) If the scores are converted into grades, with the following rules: scores below 59.5 are rated as D, scores from 59.5 to 69.5 are rated as C, scores from 69.5 to 89.5 are rated as B, and scores from 89.5 to 100.5 are rated as A. Then, among the 200 students who participated in the preliminary round, the number of students whose participation scores are rated as D is approximately ______.
