A target is made of a yellow square inside of a green square. What is the theoretical probability that a dart will hit the green square if the side length of the yellow square is 4, and the side length of the green square is 8?
The dart can hit the green square if it lands anywhere within the boundaries of the green square. The green square has side length 8, so its area is 8 x 8 = <<8*8=64>>64 square units.
The yellow square is entirely contained within the green square. Since its side length is 4, its area is 4 x 4 = <<4*4=16>>16 square units.
Therefore, the theoretical probability that a dart will hit the green square is 64 - 16 = <<64-16=48>>48 square units.
The probability is therefore 48/64 = 3/4 = <<48/64=3/4>>3/4. Answer: \boxed{\frac{3}{4}}.