One-Way ANOVA Is Performed on Independent Samples Taken from Three $n _ { 1 } =$

One-way ANOVA is performed on independent samples taken from three normally distributed populations with equal variances. The following summary statistics are calculated: $n _ { 1 } =$ 6, $\bar { x } _ { 1 } =$ 50, $s _ { 1 } =$ 5.2. $n _ { 2 } =$ 8, $\bar { x } _ { 2 } =$ 55, $s _ { 2 } =$ 4.9 . $n _ { 3 } =$ 6, $\bar { x } _ { 3 } =$ 51, $s _ { 3 } =$ 5.4. The grand mean equals: $\begin{array}{|l|l|}\hline \text { A. } & 50.0 \\\hline \text { B. } & 52.0 \\\hline \text { C. } & 52.3 \\\hline \text { D. } & 53.0 \\\hline\end{array}$