Bob is considering using a Value Stream map (VSM) to analyze the process of furnishing the interior of an office building. To evaluate the difficulty of creating a VSM, Bob gathered the following data for screwing in one sheet of drywall (4' X 8'). After observing the attachment of 40 sheets, Bob found that on average it takes 6 min for one sheet to be fully attached by one worker and on average the crew attaching drywall finishes 20 sheets per hour. At Bob's site it takes two weeks to book the drywall crew. Only 1 in 100 sheets has any problem after is attached. Bob has found that the crew only starts on schedule 10% of the time.

Use the following value stream to answer the questions below.

If there are 30 sheets of drywall between cutting and attachment, how long on average do they sit there?