Question 1063253
Suppose you pay back $510 on a $500 loan. You had the loan for 45 days. What was your simple annual interest rate?
<pre>SI = PTR
Note that number of days used for these types of calculations is 360, not 365 like most people think
{{{510 - 500 = 500 * (45/360) * R}}} 
{{{10 = 500 * (1/8) * R}}}
{{{10 = 500R/8}}}
500R = 80 ------- Cross-multiplying
R, or annual interest rate is: {{{highlight_green(matrix(1,5, 80/500, or, .16, "=", "16%"))}}}