题库搜索>问题求解PS-12759
A certain list consists of 21 different numbers. If n is in the list and n is 4 times the average (arithmetic mean) of the other 20 numbers in the list, then n is what fraction of the sum of the 21 numbers in the list?
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当前版本由 借我借我一双慧眼吧 更新于2015-12-10 11:19:02 感谢由 借我借我一双慧眼吧 对此题目的解答所做出的贡献。题目说有21个不同的数字，n是其中之一，n是剩下20个数字平均值的四倍，n是总共21个数的多少？
设平均值为k 则剩下20个数字的平均值为20k
n是平均值的四倍 n=4k
则 4k/20k+4k=1/6
N是其他20个数平均数的4倍；
所以这里可以求出n:设平均数为a：n=4a
所以21个数的中和就应该是：20a+4a=24a
所以：4a/24a=1/6
296823cl
假設20個數平均為1 n是平均值的4倍 n=4,n的佔比就會為4/(20+4)=1/6
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2021-07-25 17:06:37
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