Answer:
The radius should be increased by 0.295 inches.
Step-by-step explanation:
Volume of a cylinder:
In a cylinder, in which the base has radius
, and the height is
, the volume is given by:

In this question:
5 inch height, radius of 2.5 inches. So the volume is given by:

We want to increase the volume by 25%.
So, the new volume is given by:

With this volume, keeping the height, the radius should be of:






The radius should be of 2.795 inches, which is an increase of 2.795 - 2.5 = 0.295 inches.