Suppose There Are 28 Samples Obtained at Equally Spaced Time $b _ { 7 }$

Multiple Choice

Suppose there are 28 samples obtained at equally spaced time points, and n=7 observations in each sample. If the sum of the 28 sample ranges is 98, and that the tabulated values of $b _ { 7 }$ and $c _ { 7 }$ are 2.706 and .833, respectively, then the 3-sigma control limits LCL and UCL for an R control chart are respectively

A) 0.0 and 6.73
B) .27 and 6.73
C) -30.61 and 37.61
D) 0.0 and 37.61
E) None of the above answers are correct.