Table $13-11$

Teacher's Helper is a small company that has a subcontract to produce instructional materials for disabled children in public school districts. The owner rents several small rooms in an office building in the suburbs for $$600$ a month and has leased computer equipment that costs $$480$ a month.

$\backslash$table$[[$Output $($Instructional Modules per Month$),\backslash$table$[[$Fixed$],[$Costs$]],$Variable Costs,$\backslash$table$[[$Total$],[$Cost$]],\backslash$table$[[$Average$],[$Fixed$],[$Cost$]],\backslash$table$[[$Average$],[$Variable$],[$Cost$]],\backslash$table$[[$Average$],[$Total$],[$Cost$]],$Marginal Cost$],[0,$$$1,080,,,,,,],[1,$$$1,080,$$ $400,$$$1,480,,,,$$$400],[2,,,,,,$$$965,$$$450],[3,,$$$1,350,$$$2,430,,,,],[4,,$$$1,900,,,$$$475,,],[5,,$$$2,500,,$$$216,,,],[6,,,$$$4,280,,,,$$$700],[7,,$$$4,100,,,,,],[8,,$$$5,400,,$$$135,,,],[9,,$$$7,300,,,,,],[10,,,$$$10,880,,$$$980,,]]$

Refer to Table $13-11.$ What is the average variable cost for the month if $6$ instructional modules are produced?

$$ a$.$ $$533\mathrm{.}33$

$$ b$.$ $$180\mathrm{.}00$

$$ c$.$ $$713\mathrm{.}33$

$$ d$.$ $$700\mathrm{.}00$