A manufacturing firm assembles wooden toolboxes from pre-fabricated kits. The process has three stages: assembly, finishing, and packaging. They produce two models of toolboxes: the Foreman and the Chief. The production process is shown below.

Assembly: T= 4minutes/toolbox

Finishing: T+ 3.5 minutes/toolbox

Packaging: T= 3 minutes/toolbox

The production process operates 8 hours per day. The two models of toolboxes are produced in batches of 300 toolboxes at a time, and whenever the finishing process switches between the two models there is a 10-minute changeover time. The assembly and packaging processes can switch quickly between the two models and have no changeover times.

What will be the average work-in-process inventory between finishing and packaging?