First subtract your end value by initial, because all we want is the amount gained from interest. 7998 - 6450 = 1548
Next, divide that by the amount of time it took to gain that money. 1548/4 =
$337 a year.
Finally, divide your year's worth by the initial amount to get the rate in %.
337/6450 = 0.052
OR
5.2%
