Quick question

Oh ok thanks!

How do you find the common ratio of the series 

 Where the first term is 1?

That series is not a geometric progression so it does not have a common ratio.

If a series is a GP then      $\frac{t_2}{t_1}=\frac{t_3}{t_2}=\frac{t_4}{t_3}.......=\frac{t_{n}}{t_{n-1}}$

If a series really is a GP and the first term is 1 then the the common ratio would be T2