Hello!
The answer is:
![A(13)=107.37Km^(2)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/9n0g2xk25wyjc2q0pteob1c97qw30o7rtf.png)
Why?
We can calculate the area of the lake after 13 years using the following equation:
![A(t)=A(initial)(1-ShrinkingRate)^(t)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/ud9gagruh8khdfnv74xqa5vdz6e956u4g0.png)
Where,
A(t), is the area after t time (years)
A(Initial), is the initial area
Shrinking Rate, is the rafe of shrinking and it's 6% or 0.06.
t, is the time
So, substituting we have:
![A(13)=240(1-0.06)^(13)=240*0.447=107.37Km^(2)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/e8bd3prsbjaqtu5vx19iuco8ptccudin1y.png)
So, the are after 13 years will be:
![A(13)=107.37Km^(2)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/9n0g2xk25wyjc2q0pteob1c97qw30o7rtf.png)
Have a nice day!