documentclass[12pt, a4paper]{article}
usepackage[
a4paper,top=0.7in,bottom=0.4in,left=0.7in,right=0.6in]{geometry}
usepackage[utf8]{inputenc}
usepackage[misc]{ifsym}
usepackage{amsmath}
usepackage{amsfonts}
usepackage{mathtools}
usepackage{parskip}
usepackage{amssymb}
usepackage{forest}
usepackage{tikz}
usepackage{tkz-euclide}
usetkzobj{all}
usetikzlibrary{intersections}
headsep=10pt
begin{document}
large
begin{center}
    begin{tabular}{|c|c|c|c|}
    hlinerule[-1.2ex]{00pt}{5ex}
    Class & $(f_i)$ &  $(x_i)$ & $f_i cdot x_i$      \ hline
    $0 - 2$          & $1$                      & $1$                & $1$                  \ hline
    $2 - 4$          & $2$                      & $3$                & $6$                  \ hline
    $4 - 6$          & $1$                      & $5$                & $5$                  \ hline
    $6 - 8$          & $5$                      & $7$                & $35$                 \ hline
    $8 - 10$         & $6$                      & $9$                & $54$                 \ hline
    $10 - 12$        & $2$                      & $11$               & $22$                 \ hline
    $12 - 14$        & $3$                      & $13$               & $39$                 \ hline rule[-1.2ex]{0pt}{4ex}
    Total            & $sum f_i = 20$          &                    & $sum f_i x_i = 162$ \ hline
end{tabular}
end{center}
end{document}