Using the values given there (an aluminum beam, 0.5128 m x 25.5 mm x 3.2 mm, E = 6.9 x 1010 N/m2 , ρ = 2715 kg/m3 , A = 8.16 m2 , and I = 6.96 x 10-11 m4 ), compute the first four natural frequencies as accurately as possible and compare them to both the analytical values and the measured values.