请详细解答下这一道题，生成完整的解答思路和结果---**Question 7** **Question Stem:** 7. 如图, 正方体ABCD – EFGH的一个截面经过顶点A, C及棱EF上一点K, 且将正方形分成体积比为3:1的两部分, 则$\frac{EK}{KF}$的值为____. **Translation of Question Stem:** 7. As shown in the figure, a cross-section of the cube ABCD – EFGH passes through vertices A, C and a point K on edge EF, and divides the cube into two parts with a volume ratio of 3:1. What is the value of $\frac{EK}{KF}$? **Mathematical Formulas/Expressions:** * Ratio of volumes: 3:1 * Ratio to find: $\frac{EK}{KF}$ **Chart/Diagram Description:** * **Type:** A three-dimensional geometric figure, specifically a cube (正方体). * **Main Elements:** * **Vertices:** The cube has 8 labeled vertices: * Bottom face vertices: A, B, C, D. Vertex A is in the front-left, B in the front-right, C in the back-right, and D in the back-left (from the viewer's perspective). * Top face vertices: E, F, G, H. Vertex E is directly above A, F above B, G above C, and H above D. * **Edges:** All edges of the cube are drawn. Visible edges are solid lines (e.g., AB, BC, AE, BF, FG, GC, GH, HE). Hidden edges (edges that would be obscured by the cube's faces from this viewpoint) are represented by dashed lines (e.g., AD, DC, DH). * **Point K:** A point K is marked on the top edge EF, located between E and F. * **Construction Line:** A dashed line segment connects point K to point D. This suggests that the cross-section passes through D as well, forming a plane ACK (or ACK-related shape).