The coefficient of volume expansion γ ≈ ΔV/(VΔT). Since density ρ=m/V, for a small change, Δρ/ρ ≈ -ΔV/V. So, γ ≈ -(Δρ/ρ)/ΔT = -(-0.001)/100 = 10⁻⁵ /°C. The coefficient of linear expansion α = γ/3 = 10⁻⁵/3 ≈ 3.3×10⁻⁶ /°C.