1986 AMC 8 第 12 题
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所有题目均经美国数学协会（MAA）官方合法授权使用。
12.
图表显示了一个数学班 名学生在最近两次测验中的成绩分布。例如，正好有一名学生在测验 中得“D”，在测验 中得“C”（圈出的格子）。有百分之多少的学生两次测验得到了相同成绩？
The table shown displays the grade distribution of the students in a mathematics class on the last two tests. For example, exactly one student received a ‘D’ on Test and a ‘C’ on Test (the circled entry). What percent of the students received the same grade on both tests?
小提示：
两次成绩相同的学生位于表格从左上到右下的对角线上
A student with the same grade on both tests lies on the diagonal running from the top-left to the bottom-right of the table
大提示：
把对角线上的数相加，再除以 ，并转成百分数
Add the diagonal entries, then divide by and convert to a percent
解答：
学生两次测验成绩相同，正对应主对角线上的格子。这些数是 。
所以比例是 。
所以正确答案是 D。
A student received the same grade on both tests exactly when counted on the main diagonal. Those entries are
So the fraction is
Thus, the correct answer is D .
其他年份的第 12 题
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