We have the following equation to find the simple interest given a rate r at a time t:
[tex]I=C\cdot r\cdot t[/tex]where C represents the initial amount.
In this case, we have the following:
[tex]\begin{gathered} C=4000 \\ t=4.5\%=0.045 \\ t=6 \\ \Rightarrow I=4000(0.045)(6)=1080 \\ I=1080 \end{gathered}[/tex]therefore, the interest after 6 years will be $1080
