某建筑公司具有近期混凝土强度的统计资料10组如下:31.4、30.68、30.8、31.57、32.13、33.5、32.02、28.1、34.67、35.43。现要求配制C30级混凝土,求应配制混凝土的强度为多少?
解:
混凝土的强度标准差
取σ=3.0(N/mm2)
Goods are carried by several of transport--on road or rail, by sea or air.
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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