The regular period is 2pi. If you look up or type in a graphing calculator you can see that's when the sine function starts to repeat itself.
1. Balance after 1 year with simple interest= 600 + (2.5 x 12) = 600 + 30 = $630
2. Balance after 1 year with compounded interest = P ( 1 +
= 600 ( 1 + = 600 (1.0511) = $630.66 = approx. $630
You have to use the substitution method by substituting one Y value with the other