Calculate No. of Spheres to Cover 50% of a 25m^2 Square

[mkbh_10]

If I have a square surface of 25 m^2 and I want to know how many sphere of radius r will cover 50% of the area, then how to proceed ?

Should I calculate the area of circle which will form by projecting a sphere on a 2D surface, and divide 12.5 m^2 by this area to get the no. of spheres ?

 

[HallsofIvy]

If by "covering" you mean the sphere is directly above the area "covered" then, yes. A sphere of radius r "covers" a circle of radius r so area \pi r^2.