Question

What is the common ratio in this geometric sequence 3, 18, 108, 648, 3888, ...?

Answer 1

The ratio is `6`.

Explanation:

A term in a geometric series are obtained by multiplying the previous one by a fixed value, called ratio, which we will call `r`.

So, the second term `18` is obtained by the first, `3`, multiplying by a value which we can easily find: if `18=3*r`, then `r=18/3=6`.

The same goes for the third, since `108=18*6`, and so on.

You can check that also the reimaining terms obey this rule, so the ratio is `6`.