i understand how to do the problem. i am struggling on why the beam is W 14x48 with the Sr being 55.3 in^3

362 2 7) Select the lightest adequate W-section with a nominal depth of 14 in or less.fora 328 beam with a total uniformly distributed load of 1200 lb/ft. Select the beam based on bending stress then check to see if deflection is O.K. LL Allowable deflection = 1/360 Fb = 2/3 Yield strength for mild, low carbon steel (as listed in appendix) LL is 70% of total load M max = 153.6 k-It Sr- 55.3 in Selection = W14x48 ALL allow = _1.07 in LL max = _ _1.41 in Deflection O.K. NO NOT bring to Testing Center Table 1-1 Votes in Customary Valta 0 Beem 18.3 93.5 765 72.1 70.9 S08 383 34.7 Delo W36 x 300 W33 X 318 W36 x 360 W36 x 245 W33 x 241 W30 x 173 W33 x 130 W33 x 118 W30 x 108 W21 X 132 W24 X 117 W30 x W27 X 102 W18 X 130 W30 X 90 W21 X 101 W27 X 84 W24 X 76 W21x W24 x 68 31.7 16.655 15.965 16SSO 16510 15.860 14.965 11 SIO 11.400 10.475 12440 12.800 10.450 10.015 11.160 10.400 12.290 9.960 8.990 8.353 W18 X 76 WI4 X 90 W21 X 62 W18 X 65 W16 X 67 W21 x 50 W16 X 57 W21 X 44 W18 x 46 W14 X 48 WI8 x 40 W12 x 50 WI8 x 35 W16 x 31 W12 x 35 W12x 26 wio x 30 W14 x 22 W12 X 16 W12 x 14 W10 * 12 W8 x 10 W6 X 12 38.8 34A 29.1 30.0 38.2 26.4 29.8 24.8 22.4 24.3 20.1 223 26 $ 18.3 19.1 19.7 14.7 16.8 13.0 13.5 14.1 11.B 14.7 10.3 9.12 10.3 7.65 8.84 6.49 4.71 4.16 3.54 2.96 3.35 36.74 35.16 36.26 36.00 3418 30.44 33.09 32.89 29.83 21.83 24.26 29.65 27.09 19.25 29.53 21.36 26.71 23.92 21.43 23.73 18.21 14.02 20.99 18.35 16.33 20.83 16.43 20.66 18.06 13.79 17.90 12.19 17.70 15.88 12.50 1222 10.47 13.74 11.99 11.91 9.87 7.89 6.03 8.965 11.035 14.520 8.240 7.590 10.235 6.530 7.120 6.500 6.060 8.030 6.015 8.080 6.000 5.525 6.560 6.490 5.810 5.000 3.990 3.970 3.960 3.940 4.000 1 110 1 110 953 895 129 599 406 359 299 295 291 269 267 256 245 227 213 176 171 154 146 14 127 117 117 94.5 92.2 81.6 78.8 70.3 684 647 576 472 45.6 334 324 29.0 17.1 149 10.9 7.81 731 20 300 1 300 19 500 1 290 17300 1090 16 100 1 010 14200 932 8200 590 6710 218 5 900 187 4470 146 3220 333 3 540 297 3 990 128 3620 139 2460 278 3620 115 2420 248 2850 105 2 100 825 1 830 81.4 1 830 70.4 1 330 152 999 362 1 330 37.5 1070 54.8 954 119 984 24.9 758 43.1 843 20.7 712 22.5 485 SIA 612 19.1 394 56.3 510 15.3 375 12.4 283 24.5 204 17.3 170 16.7 7.00 103 2.82 88.6 2.36 53.8 30.8 2.09 221 2.99 199 2.18