1) Bucket can hold at least 9 liters of water, but doesn't give any info regarding the capacity of the bucket
Insufficient

2)Let x be the capacity of the Bucket
Given that Bucket contains x/2 liters
When 3 liters is added water content increased by 1/3
(x/2) + 3 = (x/2)*(1/3)
x/6 = 3
x = 18
Sufficient

So, B alone is sufficient

BTGmoderatorDC wrote:Marcia's bucket can hold a maximum of how many liters of water?

(1) The bucket currently contains 9 liters of water.
(2) If 3 liters of water are added to the bucket when it is half full of water, the amount of water in the bucket will increase by 1/3.
Source: Official Guide

$$? = C\,\,\,\,\left[ {{\rm{capacity}}\,\,{\rm{in}}\,\,{\rm{liters}}\,\,{\rm{of}}\,\,{\rm{water}}} \right]$$
$$\left( 1 \right)\,\,9\,\,{\rm{liters}}\,\,\,\left\{ \matrix{
\,\,{\rm{full}}\,\,\, \Rightarrow \,\,\,{\rm{?}}\,\,{\rm{ = }}\,\,{\rm{9}}\,\, \hfill \cr
\,\,{\rm{not}}\,\,{\rm{full}}\,\,\, \Rightarrow \,\,\,{\rm{?}}\,\,{\rm{ > }}\,\,{\rm{9}}\,\, \hfill \cr} \right.\,\,\,\,\, \Rightarrow \,\,\,\,\,\,{\rm{INSUFF}}.$$
$$\left( 2 \right)\,\,\,{C \over 2} + 3\,\, = \,\,\left( {1 + {1 \over 3}} \right){C \over 2}\,\,\,\,\,\,\, \Rightarrow \,\,\,\,{C \over 2}\,\,{\rm{unique}}\,\,\,\,\,\, \Rightarrow \,\,\,\,\,\,{\rm{SUFF}}{\rm{.}}$$

This solution follows the notations and rationale taught in the GMATH method.

Regards,
Fabio.