To find any term
of a geometric sequence:
where a1 is the first term of the sequence,
r is the common ratio, n is the number of the term to find.
a5 = a1 * r^4;
36 = a1 * (1/3)^4;
a1 = 36 * 81;
a1 = 2916;
a10 = a1 * r^9;
a10 = 2916 * (1/3)^9;
a10 = 2916/13122;
a10 = 36/243;
Finally, a10 = 4/27;
