3. If the circumference of the top base of a frustum is $4 \pi$, and the circumference of the bottom base is $9 \pi$, and the circumference of a section parallel to the bases is the geometric mean of the circumferences of the top and bottom bases, then the ratio of the two segments of the height of the frustum divided by this section is $\qquad$ -
3. $2: 3$,