A company just starting business made the following four inventory purchases in June:

$\backslash$table$[[$June $1,150$ units,$$2\mathrm{.}60$ each,$$390$ total cost$],[$June $10,200$ units,$$2\mathrm{.}925,585],[$June $15,200$ units,$$3\mathrm{.}15,630],[$June $28,150$ units,$$3\mathrm{.}4,\frac{510}{?}$