Answer:
It increased by a factor of 3.
Step-by-step explanation:
The gravitational potential energy of an object is given by
![U=mgh](https://img.qammunity.org/2020/formulas/physics/middle-school/awmf2k5psn5kpap0fanr9ig88pgdkkr3bv.png)
where
m is the mass
g is the gravitational acceleration
h is the heigth of the object relative to some reference point (for instance, the ground)
As we see from the formula, the gravitational potential energy is directly proportional to the mass, m: therefore, if the mass of the cylinder is increased by a factor 3, then the gravitational potential energy will also increase by a factor 3.