9514 1404 393
Answer:
17.98
Step-by-step explanation:
The sequence is geometric with first term a1 = 12 and common ratio r = 1/3. Put these numbers in the formula and do the arithmetic.
[tex]S_n=a_1\cdot\dfrac{1-r^n}{1-r}\\\\S_6=12\cdot\dfrac{1-\dfrac{1}{3^6}}{1-\dfrac{1}{3}}=12\cdot\dfrac{3}{2}\cdot\dfrac{728}{729}=\dfrac{1456}{81}\approx\boxed{17.98}[/tex]
