<image> A school in Changchun is planning an outing for seventh-grade students, with the following destinations available: Northeast Tiger Park, Jingyuetan, Changying Century City. Each student can only choose one of these destinations. The student council randomly selected a students from the seventh-grade students to survey which destinations they chose, and based on the survey results, the following bar graph was created. 
(1) Find the value of a;
(2) Find the percentage of these a students who chose to go to Jingyuetan;
(3) Based on the survey results, estimate the number of seventh-grade students choosing to go to Jingyuetan out of 650 students in the school.