we know that
the scale is 2 cm/1 km
on a map, the area of a forest preserve is 3.8 cm²
assuming it has a square shape
the length side of the square is √3.8 cm
so
if 2 cm on a map-----------------> is a 1 km in the actual
√3.8 cm------------------------> x
x=√3.8/2 km
the area of the actual forest preserve is
(√3.8/2)*(√3.8/2)----> 3.8/4---> 0.95 km²
the answer is
0.95 km²