Shewhart control chart is composed of three factors: center line, upper control limit$,$ and lower control limit$,$ which is described in below formula:

UCL $=$ mu$\_\{$w$\}+$ L$*$sigma$\_\{$w$\}$ Center line $=$ mu$\_\{$w$\}$ LCL $=$ mu$\_\{$w$\}-$ L$*$sigma$\_\{$w$\}$

Which one of the following is NOT true about the symbol $"$L$"$ in the formula?

It is the distance of the control limit from the center line.

It is the number of standard deviation of sampling distribution.

Typical value for $7$ deg $*$ Is $*3$

It can take on the value of O if process is in control.