AMC 8 2003 Problem 7

AMC8 2003 年第 7 题

表达式与运算★★☆☆☆

Blake and Jenny each took four 100 -point tests. Blake averaged 78 on the four tests. Jenny scored 10 points higher than Blake on the first test, 10 points lower than him on the second test, and 20 points higher on both the third and fourth tests. What is the difference between Jenny's average and Blake's average on these four tests?

Blake 和 Jenny 每人参加了四次满分为 100 分的测验。Blake 在四次测试中平均得分为 78 分。 Jenny 在第一次测试中比 Blake 高 10 分，在第二次测试中比他低 10 分，在第三次和第四次测试中都比他高 20 分。那么 Jenny 和 Blake 在这四项测试中的平均分的差是多少？

A.10
B.15
C.20
D.25
E.40

正确答案 · Correct Answer

解析 · Solution

Solution 1

Blake scored a total of 4×78 = 312 points. Jenny scored 10-10+20+20 = 40 points higher than Blake, so her average is

\displaystyle \frac{312+40}{4} = 88

. the difference is

88-78=\mathrm{(A)10}

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