In a weighted least squares optimization, we wish to find a constant $c^*$ that minimizes the weighted sum of squared deviations: $f(c) = \sum_{i=1}^n w_i (x_i - c)^2$, where $w_i > 0$. Identify the statistic $c^*$ represents and compute its value for the dataset $X = \{10, 20, 30\}$ with weights $W = \{1, 2, 3\}$.