Clearing concepts for compound interest A man banked $\$50,000$ into the bank which pays compound interest if $7.6\%$ per annum compounded every 3 months. 
The formula is 
$$ A = P \left( 1 + \frac r {100} \right)^n $$
where $P$ is the principal amount, $r$ is the rate of interest annually, and $n$ is the number of years.
For that question 


*

*Why do I have to take $r =7.6/4$ when it is every 3 months ? 

*So if the question wants "compounded quarterly." Do I take $r = 7.6/3$ ? 
So in conclusion , for 'R' do I divide the number of times they get the interest per year ? For example compounded every 3 months , 1 year they will get interest 4 times . That is why I divide by 4 . 

$7.6\%$ per year $= \dfrac{7.6\%} 4$ per quarter, since there are four quarters in a year.  And if $n$ is the number of years, then $4n$ is the number of quarters.  So you have
$$
\left( 1 + \frac{7.6/4}{100} \right)^{4n}.
$$
