Answer: Yes, the posture will be lie flat in the box.
Explanation:
since we have given that
Area of square framed poster = 9 sq. feet
Volume of cube shaped box = 30 cubic feet.
As we know the formula for "volume of cube":
![Volume=30\\\\a^3=30\\\\a=\sqrt[3]{30}=3.10\ feet](https://img.qammunity.org/2018/formulas/mathematics/high-school/1t861py5xjpdii65uj9804b12crggds08u.png)
So, Area of cube shaped box would be

Since the cube box is large enough so that the posture will lie flat in the box.