AMC 8 1990 Problem 20
AMC8 1990 年第 20 题
统计与数据图表★★★☆☆
The annual incomes of 1,000 families range from $8200 to $98,000 . In error, the largest income was entered on the computer as $980,000 . The difference between the mean of the incorrect data and the mean of the actual data is
1,000 个家庭的年收入范围为 $8200 到 $98,000。错误地将最大收入输入为 $980,000。错误数据的平均数与实际数据的平均数之差为
- A.$882
- B.$980
- C.$1078
- D.$482,000
- E.$882,000
正确答案 · Correct Answer
A
解析 · Solution
Solution 1
The sum of the incorrectly entered incomes is $980000-$98000=$882000 higher than the sum of the actual incomes. Therefore, the mean of the incorrect incomes is higher than the mean of the actual incomes.
Let be the sum of the correctly entered incomes. The mean of the actual incomes is , and for the incorrect data the mean is . The difference between these means is - = $882.
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