确定结论“X与Y有关系”的可信度为95%时,则随机变量k2的观测值k必须
A.大于10.828
B.大于3.841
C.小于6.635
D.大于2.706
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B解析分析:由表格可得当k>3.841时,有1-0.05=0.95=95%,故可确定“X与Y有关系”的可信度为95%.解答:K2>k)0.500.400.250.150.100.050.0250.0100.0050.001k0.4550.7081.3232.0722.7063.8415.0246.6357.87910.828由上表可知当k>3.841时,有1-0.05=0.95=95%故可确定“X与Y有关系”的可信度为95%.故选B.点评:本题考查独立性检验的相关程度,属基础题.