Control charts for

x R and

are maintained for an important quality characteristic. The sample size is n$=$

$7$;

x R and

are computed for each sample. After $35$ samples we have found that

$==$

$==$

$3535$

$11$

i i $7,805$ and $1,200$

i i

x R

$($a$)$ Set up

x R and

charts using these data