Question

Your mark in a class is 35%. If a test is worth 15%, and you score 60%, What is your new class mark.

Answer 1

let's say the total score is really "x", so thus far you only have in your mark 35% of "x".

now, you have a test that's going to be 15% of "x", and holly smokes, you scored a whooping 60% of that score, wait a minute!, what's 15% of "x" anyway?

`\begin{array} \cline{1-1} \textit{\textit{\LARGE a}\% of \textit{\LARGE b}}\\ \cline{1-1} \\ \left( \cfrac{\textit{\LARGE a}}{100} \right)\cdot \textit{\LARGE b} \\\\ \cline{1-1} \end{array}~\hspace{5em}\stackrel{\textit{15\% of x}}{\left( \cfrac{15}{100} \right)x}\implies 0.15x`

hmmm what's 60% of that?

`\stackrel{\textit{60\% of 0.15x}}{\left( \cfrac{60}{100} \right)0.15x}\implies 0.09x\hspace{5em}\stackrel{\textit{converting to \% format}}{0.09* 100}\implies 9\%\textit{ of`