Final answer:
The common ratio of the given geometric sequence is 6.
Step-by-step explanation:
A geometric sequence is a sequence of numbers in which each term after the first is found by multiplying the previous term by a fixed, non-zero number called the common ratio. To find the common ratio of the given sequence {3, 18, 108, ...}, we can divide any term by its previous term. Let's take the second term, 18, and divide it by the first term, 3.
18 / 3 = 6
Therefore, the common ratio of the geometric sequence is 6. Each term is obtained by multiplying the previous term by 6.