Answer:
b is the answer
Step-by-step explanation:
Formula used :
Sum of the first 4 geometric series is
[tex]s=a(\frac{1-r^4}{1-r} )[/tex]
where a=0.8 and sum= 0.8+1.3+3.0+3.2=8.3
putting value in formula,
which give equation [tex]r^4-10.357r+9.375=0[/tex]
and value of r lie between (1,1.6)
therefore, r = 1.3
