Answer:
⅕
Explanation:
Given that points X, Y, and Z are collinear, and X is said to partition segment XZ in the ratio XY to XZ = 1:5, it means that segment XY = ⅕ of XZ. That is XY/XZ = ⅕
See attachment below to understand how point Y divides segment XZ.
Therefore, the k value Brianna would use when solving the problem should be the fraction, ⅕.
k value = XY/XZ = 1/5