\( \begin{aligned} \bar{x} & =\frac{2 x_{i} \cdot f_{j}}{n} \\ \bar{x} & =\frac{x_{i} \cdot f_{1}+x_{i} \cdot f_{2}+\ldots \ldots x_{n} \cdot f^{\prime}}{n} \\ & \begin{array}{|c|c|c|} \hline & x_{i} & f_{i} \\ \hline & 4 & 18 \\ \hline & 10 & 4 \\ \hline & 18 & i \\ \hline \end{array} \end{aligned} \)

To calculate \( \bar{x} \) using the provided table, you first need to find the values of \( f_i \), represent the frequency of each \( x_i \). The values you have for \( x_i \) are 4, 10, and 18 with their corresponding frequencies of 18 and 4, but the frequency for 18 (denoted \( i \)) needs to be determined. Once you find \( i \), multiply each \( x_i \) by its corresponding frequency \( f_i \) and then sum these products for the numerator. Finally, divide this total by \( n \), where \( n \) is the total sum of the frequencies. Don't forget to check your calculations at each step to avoid mistakes, like adding frequencies incorrectly or misplacing a multiplication! It’s all about balancing numbers like a tightrope walker—one misstep could lead you off course!