Verified answer

∆L/L = α∆T, α is linear thermal expansion coef

∆A/A = 2α∆T

∆V/V = 3α∆T

linear thermal expansion coef Al 23.1e-6 /K

∆A = A2α∆T

3.9e-6 = 0.51(23.1e-6)(∆T)

∆T = 0.33ºC

T = 25.33ºC

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