Question 1205016
<br>
(Informally....)<br>
The sum of the first 3 terms is 8, and the sum of the first 6 terms is 12.<br>
That means the sum of terms 4, 5, and 6 is 12-8 = 4.<br>
The 4th term is equal to the 1st term multiplied by the common ratio 3 times; similarly for the 5th and 2nd, and for the 6th and 3rd.  So the sum of terms 4, 5, and 6 is the sum of terms 1, 2, and 3, multiplied by the common ratio 3 times.<br>
So<br>
{{{(8)(r^3)=4}}}
{{{r^3=0.5}}}
{{{r=root(3,0.5)}}}<br>
ANSWER (to a few decimal places): 0.7937<br>