ACT数学习题解析(3)

　　据留学360介绍，ACT数学习题及解析(3)！关于ACT数学同学们应该定期进行模拟练习，全面的考题使学生了解所有的题型分布，大量的练习为学生不断提高解题技巧和速度提供了保障。下面我们来看一下美国高考ACT数学题......

　　So far, a student has earned the following scores on four 100-point tests this grading period:65,73,81, and 82. What score must the student earn on the fifth and last 100-point test of the grading period to earn an average test grade of 80 for the 5 tests?

　　A. 75

　　B. 76

　　C. 78

　　D. 99

　　E. The student cannot earn an average of 80.

　　解析：The correct answer is D. To find what the student needs to score on the fifth 100-point test to average a score of 80, you need to find the point total for the student so far by adding 65,73, 81 and 82. That sum is 301. Averaging 80 points on 5 tests means the student must earn 400 points (80·5). The acore needed on the last test is the difference,400～301, or 99.

　　正确答案选D。该学生前四次共得301分;5次考试平均分为80，意味着5次考试总分需达到400分，那么该学生最后一次考试需要达到的分数为400与301的差，即99分。