Resistance R = ρL/A. Volume V = AL, and Mass m = dV. So A = m/(dL). Substituting A, we get R = ρdL²/m. Since ρ and d are constant, R ∝ L²/m. R₁:R₂:R₃ = (3²/1) : (2²/2) : (1²/3) = 9 : 2 : 1/3. Multiplying by 3 gives 27:6:1.