AMC 8 1996 Problem 12
AMC8 1996 年第 12 题
统计与数据图表★★★☆☆
What number should be removed from the list
so that the average of the remaining numbers is 6.1 ?
应该从列表 1,2,3,4,5,6,7,8,9,10,11 中移除哪个数，使剩余数的平均数为 6.1？
- A.4
- B.5
- C.6
- D.7
- E.8
正确答案 · Correct Answer
B
解析 · Solution
Solution 1
Adding all of the numbers gives us as the current total. Since there are 11 numbers, the current average is . We need to take away a number from the total and then divide the result by 10 because there will only be 10 numbers left to give an average of 6.1. Setting up the equation:
, 66 - x = 61, x = 5
Thus, the answer is
Similar to the first solution, the current total is 66. Since there are 11 numbers on the list, taking 1 number away will leave 10 numbers. If those 10 numbers have an average of 6.1, then those 10 numbers must have a sum of 10×6.1 = 61. Thus, the number that was removed must be 66 - 61 = 5, and the answer is .
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