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

Sample # Blemishes

$1$

$3$

$10$

$2$

$3$

$4$

$5$

$6$

$6$

$12$

$11$

$5$

$7$

$8$

$9$

$10$

$11$

Sample # Blemishes

$0$

$12$

$8$

$7$

$10$

$12$

$3$

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

$5.$ What is the upper control limit for the most appropriate control chart?

$6.$ What is the lower boundary value between Zone B and Zone C$?$