3. using the compound interest formula A=P(1+r/n)^n*t
you have: A = 28,000(1+0.1/4)^4*1
A = 28000 * 1.025^4
A = $30,906.76 (Compound amount)
Interest = 30906.76 - 28000 = $2,906.76
7. Using the same formula as above:
A = 12300(1+0.03/2)^2*4
A = 12300 * 1.015^8
A = 13855.86 ( Compound amount)
Interest = 13855.86 - 12300 = $1,555.86