The rule of the compound interest is
[tex]A=P(1+\frac{r}{n})^{nt}[/tex]A is the new amount
P is the initial amount
r is the rate in decimal
n is the number of the periods per year
t is the number of years
Since the rate is 7% compounded semi-annual, then
r = 7/100 = 0.07
n = 2
Since the amount after 3 years will be $11 000, then
A = 11 000
t = 3
Substitute them in the rule above to find P
[tex]\begin{gathered} 11000=p(1+\frac{0.07}{2})^{2(3)} \\ 11000=p(1.035)^6 \end{gathered}[/tex]Divide both sides by (1.035)^6 to find P
[tex]\begin{gathered} \frac{11000}{(1.035)^6}=P \\ 8948.507087=P \end{gathered}[/tex]Round it to the nearest cent (2 decimal places)
P = $8948.51
The amount invested was $8948.51