【正确答案】解：由题可知，样本容量n=3，样本组数k=15. 找出每组样本中的最大值和最小值，再按下式计算各样本的均值和极差R： 上述计算结果见表所示。 组号R 14.8434.8634.8594.8634.8430.0204.855 24.9254.8824.8914.9254.8820.0434.899 34.8664.9144.8734.9144.8660.0484.884 44.8524.8834.8804.8834.8520.0314.872 54.9204.8844.8214.9204.8210.0994.875 64.9154.9024.8984.9154.8980.0174.905 74.8874.8924.8584.8924.8580.0344.879 84.8684.8884.8424.8884.8420.0464.866 94.9044.8634.8664.9044.8630.0414.878 104.9214.9204.8944.9214.8940.0274.912 114.9144.8844.8994.9144.8840.0304.899 124.8924.8964.8874.8964.8870.0094.892 134.8664.8294.8804.8804.8290.0514.858 144.8504.8754.8724.8754.8500.0254.866 154.8674.9004.8854.9004.8670.0334.884 合 计0.55473.224 然后利用下式，计算均值平均和极差平均： 查控制图界限系数表，当n=3时，，这样，控制图的控制界限为： R控制图的控制界限为： 由以上数据，即可画出控制图，如图所示。