因?yàn)閃/C=0.5,所以W=0.5×C=0.5×500=250kg
澆一根需砼3×0.3×0.2=0.18m3 則20根需砼0.18×20=3.6m3
V=0.25×0.25×0.25=0.0156米3=15.6升