Since the nth term of any geometric sequence is:
a(n)=ar^(n-1), a(n)=nth term, a=initial term, r=common ratio, n=term number
We can set up a ratio given the points as:
54/6=(ar^3)/(ar^1)
9=r^2
r=±3 however since the 4th term is greater than the second term we know r>0 so
r=3
The common ratio is 3.