\BeginKnitrBlock{exercise}\iffalse{-91-68-101-102-105-110-105-110-103-32-111-117-114-32-109-111-100-101-108-93-}\fi{}<div class="exercise"><span class="exercise" id="exr:unnamed-chunk-110"><strong>(\#exr:unnamed-chunk-110)  \iffalse (Defining our model) \fi{} </strong></span>Write down the equation for the 3$rd$ individual, if it's in group 1.</div>\EndKnitrBlock{exercise}