CLASSIFICATION OF PRE-MARITAL SEX AMONG ADOLESCENTS USING COST-SENSITIVE WEIGHTED RANDOM FOREST ON IMBALANCED DATA - Sari, Nilam Novita; Sumargo, Bagus; Siregar, Dania; Yuliani, Endang; Sari, Citra Komang; Mahardika, Baihaqy; Fadya, Khansa Salsabil (BAREKENG: Jurnal Ilmu Matematika dan Terapan, 2026)