#### Answer

5 packages

#### Work Step by Step

We are given that the ceiling is rectangular and is 18 feet by 12 feet. Therefore, we know that the area of the ceiling is $18\times12=216$.
The ballroom will require 216 one-foot-square tiles, and each package contains 50 tiles.
$216\div50=4.32$
We can round up to 5 packages, since we will need to use at least some of the tiles in the 5th package.