So, here we have the following sequence:
[tex]3,\frac{3}{4},\frac{3}{16},\frac{3}{64},\ldots[/tex]We want to know if this sequence can be a geometric sequence or not.
For this, we could rewrite this sequence as:
[tex]\begin{gathered} \frac{3}{4^0},\frac{3}{4^1},\frac{3}{4^2},\frac{3}{4^3},\ldots \\ \to3\cdot(\frac{1}{4^{}})^0,3\cdot(\frac{1}{4^{}})^1,3\cdot(\frac{1}{4})^2,3\cdot(\frac{1}{4})^3,\ldots \end{gathered}[/tex]As you can see, this is actually a geometric sequence, whose ratio is 1/4.