Given:
a.) Joe borrowed $8000 at a rate of 10.5%, compounded monthly.
For us to be able to determine how much will he owe after 9 years, we will be using the compounded interest formula:
[tex]\text{ A = P\lparen1 + }\frac{\text{ r}}{\text{ n}})^{nt}^[/tex]Where,
A=final amount
P=initial principal balance = $8,000
r =interest rate (in decimal form) = 10.5/100 = 0.105
n=number of times interest applied per time period = compounded monthly = 12
t=number of time periods elapsed (in years) = 9
We get,
[tex]\text{ A = P\lparen1 + }\frac{\text{ r}}{\text{ n}})^{nt}[/tex][tex]\text{ = \lparen8,000\rparen\lparen1 + }\frac{0.105}{12})^{12\text{ x 9}}\text{ = \lparen8,000\rparen\lparen1 + }0.00875)^{108}[/tex][tex]\text{ = \lparen8,000\rparen\lparen1.00875\rparen}^{108}[/tex][tex]\text{ = \lparen8,000\rparen\lparen2.49616052967\rparen}[/tex][tex]\text{ A = 19,969.28423739091}[/tex][tex]\text{ A }\approx\text{ \$19,969.28}[/tex]Therefore, the answer is $19,969.28