For best sample of cement the ratio of $\mathrm{CaO}\mathrm{\%}:$$\left({\mathrm{SiO}}_2\mathrm{\%}+{\mathrm{Al}}_2{\mathrm{O}}_3\mathrm{\%}+{\mathrm{Fe}}_2{\mathrm{O}}_3\mathrm{\%}\right)$ should be x:1 what is x?

Ratio of lime (CaO) to the total oxide mixtures consisting of $\left({\mathrm{SiO}}_2+{\mathrm{Al}}_2{\mathrm{O}}_3+{\mathrm{Fe}}_2{\mathrm{O}}_3\right)$ is 2:1. If quantity of lime exceeds, then during setting of cement, cracks will be there.