假定金含量是90%,则有金的质量=a*90%克,体积=a*90%/19.3cm^3;有银a*(1-90%)=a*10%克,体积=a*10%/10.5cm^3,总体积=a*90%/19.3+a*10%/10.5cm^3;
1.若首饰的体积V>a*90%/19.3+a*10%/10.5cm^3,说明黄金含量低于90%
2.若首饰的体积V<a*90%/19.3+a*10%/10.5cm^3,说明黄金含量高于90% 。
合金的密度为100/(90/19.3+10/10.5)=17.8g/cm^3
v≤a/17.8
一般有 18K 24 K 来代表纯度 24K 是9999%的纯度