$($d$)$ For $($c$)$ using the new sampling strategy, if a u chart is suggested with a convenient unit $=100$

boards, what is the sample size n in the u chart? What are the corresponding control limits of this u

chart $($CL$,$ UCL, and LCL$,$ L$=3)?$ What are c$0$ and u$0$ when the process is in$-$control? $(1$ points$)$

$($e$)$ Continue $($c$)$ using the new sampling strategy, if at sampling time t$,$ it is found that a sample of

$400$ boards has $28$ defects, what are the monitoring statistics to be plotted in the c and u charts? $(0\mathrm{.}5$

point$)$