Alex L. answered 07/01/21
Experienced and licensed math educator w/ practical statistics exp.
So the idea of the coefficient of variation is that it's scaled with the mean (μ).
Y is proportional to X. So the mean of X is b times the mean of Y. Same deal with the standard deviation.
So let's write the coefficient of variation of X compared to Y as bσ / bμ. The b's will cancel, leaving us with σ/μ.
The coefficients of variation of X and Y are the same value.