中科新闻网什么日子放生最好:数学题`````````帮忙``````
来源：百度文库 编辑：中科新闻网 时间：2024/05/01 22:42:41
在黑板上从1开始写出一组连续的正整数，然后擦去了一个数，其余的数的平均值为602/17，则擦去的数是多少？
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设n个数 擦去的是x,
因为其余的数的平均值为35又7/17,
所以(1)n-1是17的倍数,(2)n应该在70左右.
因为17*4=68,首先试n=69,1+2+……+69=69*(69+1)/2=2415
则n-1=68,其余的数的和是68*35又7/17=2408,
2415-2408=7,所以擦去的是7.
这是一道类似的题，希望对你有所启发。