To determine the weighted average of the student's grades, you have to multiply each grade by its corresponding percentage, expressed as a decimal value, and then add the results:
[tex]weighted.average=\Sigma(x_iw_i)[/tex][tex]\begin{gathered} \text{weighted.average}=93\cdot0.30+94\cdot0.30+84\cdot0.10+78\cdot0.10+94\cdot0.20 \\ weighted\text{ average=}27.9+28.2+8.4+7.8+18.8 \\ \text{weighted average=91.10} \end{gathered}[/tex]
The weighted average is 91.10
