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, 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$)?$