Question

Alice earned $622.50 in interest on her savings in the bank before interest the account had $12,450 what is the approximate percent she earned in interest

Answer 1

If we take 12450 to be the 100%, what is 622.50 off of it in percentage then?  let's check.

$\bf \begin{array}{ccll} amount&\%\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ 12450&100\\ 622.50&p \end{array}\implies \cfrac{12450}{622.50}=\cfrac{100}{p}\implies p=\cfrac{622.50\cdot 100}{12450}$