307 Diamonds Were Sampled and Randomly Sorted into Three Groups

307 diamonds were sampled and randomly sorted into three groups of diamonds. These diamonds were randomly assigned to one of the three organizations, or groups (HRD, GIA, or IGI), that certify the appraisal of diamonds. A study was conducted to determine if the average size of diamonds reported by these three certification groups differ. A completely randomized design was used and the Bonferroni multiple comparison results are shown below. $\begin{array} { l c c } \text { CERT } & \text { Mean } & \text { Bonferroni Groups } \\ \text { HRD } & 0.8129 & \text { A } \\ \text { GIA } & 0.6723 & \text { B } \\ \text { IGI } & 0.3665 & \text { C } \end{array}$

Alpha $0.05$

Give the population mean(s) which are in the statistically largest group.
A) $\mu \mathrm { HRD }$
B) $\mu _ { \mathrm { GIA } }$
C) $\mu \mathrm { IGI }$
D) $\mu _ { \mathrm { HRD } }$ & $\mu _ { \mathrm { GIA } }$