In its first month of operations, Blossom Company made three purchases of merchandise in the following sequence:

$(1)500$ units at $$6,(2)600$ units at $$7,$ and $(3)700$ units at $$9.$ Blossom uses a periodic inventory system.

Calculate weighted$-$average unit cost.

$($Round answer to $3$ decimal places, e$.$g$.5\mathrm{.}125.)$

Weighted$-$average unit cost

$