Problem $34\mathrm{.}21===$ a concrete mix with a target compressive strength of $30$ MPa at $28$ days. You have cement with a specific gravity of $3\mathrm{.}15,$ coarse aggregate with a specific gravity of $2\mathrm{.}68,$ fine aggregate with a specific gravity of $2\mathrm{.}63,$ and water$-$cement ratio of $0\mathrm{.}5.$ Calculate the proportions of cement, coarse aggregate, fine aggregate, and water per cubic meter of concrete.