Let 
be the n'th term of the sequence.
so
is the first term, 
the second term and so on...
In a geometric sequence with
, and common ratio r, the terms are as follows:
.
.
that is, each term is its previous term times the common ratio r.
In our example
and 
so
Answer: r=0.75
so
In a geometric sequence with
.
.
that is, each term is its previous term times the common ratio r.
In our example
so
Answer: r=0.75