1. Assuming that the order contains a dozen of cookies, the time to take a rush order is the sum of cycle times for each activity: 0+6+2+9+1+0+5+2+1=26 min.
2. Assuming a two dozens order, we have to consider that for the first dozen, my roommate can start backing after I have spooned the cookies on the tray. However when backing the second order he simultaneously cools and then packs the cookies from the first order. I can start mixing the second batch without waiting for the first-batch process to be completed (she starts washing out the bowl as soon as she finishes filling the tray). Thus, to fill a complete order for two dozens of cookies will be 36 min (see Gantt chart in the appendix). So for each first dozen of cookies we need 26 min, while for each additional dozen we will need only 10 min (see Gantt chart in the appendix). So the hourly capacity is 60hr/10 min=6 dozen. For the 4 hours (240 min) we will then need ((240-26)/10)+1=22 orders.
3. The main assumption is that all orders are for one dozen cookies. Valuable time is defined as time where ma and my roommate actually are doing work. To fill each order I will need 8 min (Wash bowl & Mix (6 min) + spooning on the tray (2 min)= 8 min). My roommate’s valuable time is Preheat and prepare the oven (1 min)+ Pack (2 min)+ Payment (1 min)= 4 min. The 9 minutes of baking time and 5 minutes of cooling can be used to do further productive work.
4. We first have to consider the costs to answer this question. The costs for the ingredients and the box are the same for each batch of cookies. However, my and my roommate’s valuable time depends on the number of orders. For the first dozen we will spend 12 min of valuable time (my valuable time (8 min)+my roommate’s valuable time (4 min)) (s. Q 1). In following we consider the costs for the second and the third dozen of cookies.
For the second dozen we have to consider that the time of washing the bowl and mix remains the