What is the common ratio in the following geometric sequence? . 3, 12, 48, 192,

A 1 = 3,  a 2 = 12,  a 3 = 48,  a 4 = 192,...
This is a geometric sequence.
To find any term of a sequence we use formula:
a n = a 1 * r^( n - 1 )
a 2 = a 1 * r
12 = 3 * r
r = 12 : 3
r = 4
Also: 48 = 12 * 4 and 192 = 48 * 4
The common ratio is : r = 4