S$6\mathrm{.}10$ A process that is considered to be in control measures an ingredient in grams.

Below are the last $10$ samples $($each of size n$=5)$ taken. The population standard

deviation is $1\mathrm{.}36.$

Samples

$12345678910$

$109131012101013810$

$9991010101110812$

$1011101198108129$

Samples

$12345678910$

$91110101112810128$

$121091010998912$

a$.$ What is the process standard deviation $\backslash$sigma $?$ What is $?$

b$.$ If z$=3,$ what are the control limits for the mean chart?

c$.$ What are the control limits for the range chart?

d$.$ Is the process in control?