Let's assume the length of the box is x inches.
Given that the width is 1/4 of the length, we have:
Width = x/4
Also given that the height is 2 times the width, we have:
Height = 2(x/4) = x/2
Now, the volume of the box is 1000 cubic inches:
Volume = Length x Width x Height
1000 = x * (x/4) * (x/2)
1000 = x^3 / 8
8000 = x^3
x = 20
So, the length of the box is 20 inches, the width is 5 inches (20/4), and the height is 10 inches (20/2).
Therefore, the dimensions of the shipping box are:
Length = 20 inches
Width = 5 inches
Height = 10 inches