simple interest: i = p * r * t; compound interest would be A=p(1+r/n)^(nt)
Here, A = $500 (1.10)^2 = $605 (answer for "once per year."
Once per month:
A = $500 (1 + 0.10/12)^(12*2) = $610.20
Once per week: Can y ou figure that out? # of compounding periods is 12 per year in this problem.