$2\mathrm{.}6.$ A production line is to run at $1000$ units per month. Sales are forecast as shown in the following. Calculate the expected period$-$end inventory. The opening inventory is $600$ units. All periods have the same number of working days.

$\backslash$table$[[$Period$,1,2,3,4,5,6,,,],[$Forecast$,750,800,1050,1600,1000,850,,,],[$Planned Production,$1000,1000,1000,1000,1000,1000,,,],[\backslash$table$[[$Planned$],[$Inventory$]],600,,,,,,,,]]$