Answer:
The correct option is 1.
Step-by-step explanation:
The given geometric series is
[tex]\sum_{n=1}^{3}1.3(0.8)^{n-1}[/tex]
It means the nth term of the given geometric series is
[tex]a_n=1.3(0.8)^{n-1}[/tex] .... (1)
The nth term of an geometric series is
[tex]a_n=ar^{n-1}[/tex] .... (2)
where, a is first term and r is common ratio.
From (1) and (2), we get
[tex]a=1.3, r=0.8[/tex]
The value of r is 0.8. Therefore the correct option is 1.
