A straight wire fence has 12 equally spaced posts. The distance between the third and the sixth post is $3.3 \mathrm{~m}$. What is the length of the fence, in meters?
(a) 8.4
(b) 12.1
(c) 9.9
(d) 13.2
(e) 9.075
The correct option is (b).

Between the third and the sixth post, there are three spaces between consecutive posts. Therefore, the distance between two consecutive posts is $\frac{1}{3} \times 3.3 \mathrm{~m}=1.1 \mathrm{~m}$ and the distance between the first and the last post is $11 \times 1.1=12.1 \mathrm{~m}$.