28×4+68.25×4-49×7
=112+273-343
=42.
故答案为:42.
有七个数,平均数为49,前4个数的平均数为28,后4个数的平均数为68.25,那么第4个数为_.
有七个数,平均数为49,前4个数的平均数为28,后4个数的平均数为68.25,那么第4个数为______.
数学人气:243 ℃时间:2019-11-01 08:23:39
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