Question

rice seedlings will be planted to a 20 m x 25 m area at 20 cm x 20 cm spacing, with 2 seedlings per hill. if the area is a rectangle having 25 meter long rows what will be the resulting plant population density?

Answer 1

Since the density is obviously 2 seedlings/hill, I suspect you want the density in terms of seedlings/m^2 or something.

Since each hill occupies 400cm^2, the density is

2 seedlings/400cm^2 = 1/200 seedlings/cm^2

Maybe not too useful. In terms of m^2, that will come out

2 seedlings /(.20m)^2 = 2/.4 = 5 seedlings/m^2

The size of the garden and number of rows makes no difference, unless you have some space left unused, and you want the exact density for the garden plot.