\BeginKnitrBlock{exercise}\iffalse{-91-66-97-115-105-99-32-115-97-109-112-108-101-32-115-105-122-101-32-99-97-108-99-117-108-97-116-105-111-110-115-93-}\fi{}<div class="exercise"><span class="exercise" id="exr:unnamed-chunk-63"><strong>(\#exr:unnamed-chunk-63)  \iffalse (Basic sample size calculations) \fi{} </strong></span>How can you calculate the sample size required for a 99\% CI to have a certain width $w$?</div>\EndKnitrBlock{exercise}