Answer:
Length - 12 m, width - 8m, height - 4 m
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The relation between dimensions of the box:
- w = (2/3)l;
 - h = (1/3)l;
 - V = 384 m³.
 
Use volume equation and find the value of l:
- 384 = l*(2/3)l*(1/3)l
 - 384 = 2/9l³
 - l³ = 384*9/2
 - l³ = 1728
 - l = ∛1728
 - l = 12 m
 
Find the width and height:
- w = (2/3)*12 = 8 m
 - h = (1/3)*12 = 4 m