The turtle population will be 486 after 5 years.
<u>Step-by-step explanation</u>:
The general form of a geometric progression or geometric sequence is a, ar, ar², ar³ and so on.
where,
- a = first term
- r = common ratio
<u>The formula to find the nth term in GP is :</u>
nth term =
The given sequence 6,18,54.
In this sequence,
- The first term, a = 6
- The common ratio, r = 18/6 = 3
5th term =
⇒
⇒ 681
⇒ 486
Therefore, after 5 years the population will be 486.