Answer:
0.033 ft
Step-by-step explanation:
Let g = 32.2 ft/s2 and h be the maximum height that water can be filled before the sides shatter.
Pressure is distributed from 0 to maximum at the bottom like the following equation:

So the force generated by water pressure on the side of the tank is

where s = 6ft is the side length of the tank. This force cannot be larger than 200lb




which is undefined when

or

. The answer is then the third choice.
Im thinking it is 7 weeks.