To find the weighted average we just need to sum all the scores multiplied by their respective weight.
To find 30% of a value, is the same as multiplying by 30 and dividing by 100. As a decimal, this can be represented as 0.3.
[tex]\frac{30}{100}=0.3[/tex]
Now, doing the sum multiplying the scores by their respective weights, we have:
[tex]\begin{gathered} \bar{x}=83\times0.3+94\times0.3+84\times0.1+87\times0.1+79\times0.2 \\ \bar{x}=24.9+28.2+8.4+8.7+15.8 \\ \bar{x}=86 \end{gathered}[/tex]
The weighted average of this student is 86.
