The Accompanying Table Gives Sample Means and Standard Deviations, Each $$\bar { X }$$

Essay

The accompanying table gives sample means and standard deviations, each based on n = 6 observations of the refractive index of fiber-optic cable. Calculate the control limits for an $$\bar { X }$$ chart based on the sample standard deviations given, and comment on the behavior of the chart. [Hint: $$\sum \bar { x } _ { 2 } = 2317.07 \text { and } \sum s _ { 2 } = 30.34$$ ]