Freshly painted motorcycles are inspected for blemishes. Following are the results for inspecting $12$ samples $($each sample $=1$car $)$ at random.

$\backslash$table$[[$Sample$,$# Blemishes,Sample,# Blemishes$],[1,3,7,0],[2,10,8,12],[3,6,9,8],[4,12,10,7],[5,11,11,10],[6,5,12,3]]$

What is the value of the statistic plotted for sample $4?$

What is the upper control limit for the most appropriate control chart?

What is the lower boundary value between Zone $B$ and Zone $C?$