You Are Conducting a Study on the Blood Glucose Levels

Multiple Choice

You are conducting a study on the blood glucose levels of 9 patients who are on strict diets and exercise routines.To monitor the mean and range of the blood glucose levels of your patients, you take a blood glucose reading every day for each patient for 20 days.The results are shown below.
$$\begin{array} { l r c l l l } \text { Day } & \text { Mean } & \text { Range } & \text { Day } & \text { Mean } & \text { Range } \\1 & 92.11 & 80 & 11 & 100.70 & 89 \\2 & 90.67 & 77 & 12 & 96.67 & 77 \\3 & 89.44 & 73 & 13 & 97.33 & 75 \\4 & 93.33 & 81 & 14 & 95.89 & 80 \\5 & 89.44 & 71 & 15 & 98.89 & 68 \\6 & 110.20 & 90 & 16 & 101.22 & 88 \\7 & 104.10 & 120 & 17 & 107.33 & 81 \\8 & 108.20 & 93 & 18 & 108.00 & 95 \\9 & 107.70 & 98 & 19 & 106.89 & 77 \\10 & 112.70 & 145 & 20 & 109.89 & 80\end{array}$$
The lower control limit for your $\bar { x }$ chart is ________.

A) 89.44
B) 92.11
C) 73
D) 71.75
E) 60.5