https://zh.nguoilontuoi.com/post/25-of-the-students-in-the-three-year-math-section-test-scored-95-points-35-scored-80-points-20-scored-75-points-and-the-rest-scored-50-points-what-is-the-average-score-for-the-section-test
三年一班數學段考有25%的人考95分35%的人考80分20%的人考75分其餘的人考50分則段考的數學平均分數是幾分