Quick questions on Congruence and similarity explained: O-Level E-Maths

The linear scale factor $k$ is the ratio of a length in one figure to the corresponding length in the other:

A common E-Maths task is to justify similarity before using it, and the cleanest argument lists two pairs of equal angles (AA). Equal angles often come from shared angles, vertically opposite angles, or the equal corresponding and alternate angles created by parallel lines. In a figure where a line is drawn parallel to one side of a triangle, the smaller triangle it cuts off is similar to the whole, because the parallel line produces two pairs of equal angles. Writing out the reason for each equal angle, then concluding "two pairs of equal angles, so the triangles are similar (AA)", is the structured justification markers expect.

Two similar rectangles have lengths $4\ \text{cm}$ and $10\ \text{cm}$. State the linear scale factor from the smaller to the larger. [1 mark]

The linear scale factor between two similar shapes is $3$. State the area scale factor. [1 mark]

Two similar solids have volumes in the ratio $8 : 27$. Find the ratio of their corresponding lengths. [2 marks]