AMC12 2015 A
AMC12 2015 A · Q3
AMC12 2015 A · Q3. It mainly tests Averages (mean).
Mr. Patrick teaches math to 15 students. He was grading tests and found that when he graded everyone's test except Payton's, the average grade for the class was 80. After he graded Payton's test, the class average became 81. What was Payton's score on the test?
帕特里克先生教 15 名学生数学。他批改试卷时发现，除了佩顿的试卷外，全班平均分为 80。批改完佩顿的试卷后，全班平均分变为 81。佩顿的试卷分数是多少？
(A)
81
81
(B)
85
85
(C)
91
91
(D)
94
94
(E)
95
95
Answer
Correct choice: (E)
正确答案：（E）
Solution
The sum of the 14 test scores was $14 \cdot 80 = 1120$. The sum of all 15 test scores was $15 \cdot 81 = 1215$. Therefore Payton's score was $1215 - 1120 = 95$.
14 份试卷的总分是 $14 \cdot 80 = 1120$。15 份试卷的总分是 $15 \cdot 81 = 1215$。因此佩顿的分数是 $1215 - 1120 = 95$。
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