Kirsten Cookie Case
Essay title: Kirsten Cookie Case
Solution to Kristens Cookie Company (A)
Before answering specific questions, it is useful to make a diagram of the overall process:
Note that in this diagram, activities are arranged in columns to indicate which resources are being used. Inside each activity symbol are written the capacity (in dozens of cookies) and the cycle time (in minutes).
1. How long will it take for you to fill a rush order?
Assuming this order is for one dozen cookies, we will need to do the following:
Activity
Resource
Cycle Time
Start Time
Finish Time
Order Entry
E-mail
0 minutes
00:00
00:00
Wash Bowl, Mix
6 minutes
00:00
06:00
Fill Tray
2 minutes
06:00
08:00
Prepare Oven
Roommate
1 minute
08:00
09:00
9 minutes
09:00
18:00
Remove
Roommate
0 minutes
18:00
18:00
5 minutes
18:00
23:00
Pack, Collect Money
Roommate
3 minutes
23:00
26:00
Therefore, the minimum time to fill an order is 26 minutes. We can illustrate the sequence of events with a Gantt chart:
2. How many orders can you fill in a night, assuming you are open four hours each night?
Here is a Gantt chart for two batches of one dozen cookies each. It doesnt take twice as long to produce two batches as it does to produce one batch, because you can start mixing the second batch without having to wait for the whole first-batch process to be completed (you can start washing out the bowl as soon as you finish filling the tray). It is possible to produce two batches in 36 minutes.
In general, a formula for the number of minutes to produce n one-dozen batches is given by this expression:
3. How much of your own and your roommates valuable time will it take to fill each order?
For yourself:
Activity
Cycle Time
Wash Bowl, Mix
6 minutes
Fill Tray
2 minutes
Total
8 minutes
For your roommate:
Activity
Cycle Time
Prepare Oven
1 minute
Remove
0 minutes
Pack, Collect Money
3 minutes
Total
4 minutes
This is assuming all orders are for one dozen cookies.
4. Because your baking trays can hold exactly one dozen cookies, you will produce and sell cookies by the dozen. Should you give any discount for people who order two dozen cookies, three dozen cookies, or more? If so, how much? Will it take any longer to fill a two-dozen cookie order than a one-dozen cookie order?
First, lets consider costs. The cost of ingredients and the box are the same, no matter how many dozen you bake. So the only resource that might differ with the size of the batch is labor.
One Dozen
Activity
Resource
Cycle Time
Start Time
Finish Time
Order Entry
E-mail
0 minutes
00:00
00:00
Wash Bowl, Mix
6 minutes
00:00
06:00
Fill Tray
2 minutes
06:00
08:00
Prepare Oven
Roommate
1 minute
08:00
09:00
9 minutes
09:00
18:00
Remove
Roommate
0 minutes
18:00
18:00
5 minutes
18:00
23:00
Pack, Collect Money
Roommate
3 minutes
23:00
26:00
Roommate
Total Labor Minutes
Two Dozen
Activity
Resource
Cycle Time
Start Time
Finish Time
Order Entry
E-mail
0 minutes
00:00
00:00
Wash Bowl, Mix
6 minutes
00:00
06:00