Question

Thaddeus shakes his head as he pays $12.37 to the clerk for lunch. Complaining to a friend, Thaddeus says, “Do you realize that is 0.2% of my monthly income?” His friend replies, “I think you made a mistake. That should be 2%. You messed up on the decimal point.” (a) Assuming Thaddeus is not wrong, what is his monthly income? (b) If Thaddeus’ friend is correct, what is Thaddeus’ monthly income?

Answer 1

a)

his income must be "x" which is the 100%, and we would know that 0.2% of that is 12.37.

$\begin{array}{ccll} amount&\%\\ \cline{1-2} x&100\\ 12.37&0.2 \end{array}\implies \cfrac{x}{12.37}=\cfrac{100}{0.2}\implies 0.2x=1237 \\\\\\ x=\cfrac{1237}{0.2}\implies x=61.85$

b)

his income must be "x" which is the 100%, and we would know that 2% of that is 12.37.

$\begin{array}{ccll} amount&\%\\ \cline{1-2} x&100\\ 12.37&2 \end{array}\implies \cfrac{x}{12.37}=\cfrac{100}{2}\implies 2x=1237 \\\\\\ x=\cfrac{1237}{2}\implies x=618.5$

btw he's not making much either way.