Help in case study,

case study is Kristen's Cookie Company case Assume that

the roommate is sick so Kristen has to set the timer, pack and accept payment herself

$($on top of her usual tasks$)$; all orders are for two dozen cookies; starting at

$8$ pm until midnight, a customer places an order every $30$ minutes $($ that is the first customer places an order at $8$pm$,$the second places an order at $8$:$30$ pm$,$ the third places an order at $9$pm$,$etc. until the last order at midnight$)$; customers are there to pay for the orders as soon as they are completed. for washing and mixing together step it takes

$6$minutes$,$ mixer can hold and mix ingredient for upto three dozen cookies, as for one dozen cookies, spooning cookies onto tray takes $2$minutes per tray, till here all the steps are perfomed by kristens. Now her roomate will perfome rest of the next steps set the thermostat ane timer is about $1$minute$,$ cookies baking takes $9$minutes $($can be done by oven$),$ cookie cooling time is $5$minutes$,$ it takes $2$minutes to pack each dozen cookies and about $1$minutes to accept payment fo the order. what is the average number of orders that are being processed at one moment in time $($we say that an order is $$being processed$$ if it has been placed but has not yet been completed and paid for$)?$