Answer
The common ratio is $s^{\frac{2}{7}}$.
The 5th term is $s^{\frac{8}{7}}$.
$a_{n} = 1(s^{\frac{2}{7}})^{n-1}$ (or just $a_{n} = (s^{\frac{2}{7}})^{n-1}$
Work Step by Step
We are given the terms 1 $s^{\frac{2}{7}}$ $s^{\frac{4}{7}}$ $s^{\frac{6}{7}}$
Each term is multiplied by $s^{\frac{2}{7}}$ to get to the next so the common ratio is $s^{\frac{2}{7}}$. To get the fifth term multiply the fourth term by the common ratio: $s^{\frac{6}{7}} \times s^{\frac{2}{7}} = s^{\frac{8}{7}}$.
To express the nth term of the geometric function in the form $a_{n} = a(r)^{n-1}$, plug in the first term (1) for a and the common ratio ($s^{\frac{2}{7}}$) for r to get $a_{n} = 1(s^{\frac{2}{7}})^{n-1}$
