From the question it is given that,
The length of a rectangular field is twice its breadth = 2b
Perimeter of rectangular field = 6km/4
= 1.5 km
We know that, perimeter of rectangle = 2 × (length + breadth)
1.5 = 2 × (2b + b)
1.5 = 2 × 3b
1.5 = 6b
b = 1.5/6
b = 0.25 km
length of rectangle field = 2 × 0.25 = 0.5km
= 0.5 × 1000
= 500 m
