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I only have $25 left in my account. Want to take a crack at these?...
I only have $25 left in my account. Want to take a crack at these?
Final Exam – Module 3 Questions
Please submit your answers via the Module 3 web form on the Coursera site.
Wind Tunnel Testing – Carbon Bike Frames
As an equipment provider for several Olympic cyclists, Carbon Bike Frames (CBF) operates a
very expensive wind tunnel facility near San Diego, CA. The wind tunnel is used to find the best
compromise between ergonomics and aerodynamics for the cyclist. Presently, more and more
cyclists are interested in CBF’s services, so the company considers building a second facility.
However, given the enormous costs of the wind tunnel, they also want to explore a more
effective use of the current facility. An initial data collection reveals that:
The standard fitting time for a cyclist is 2h. On average, the wind tunnel is used for 7
fitting procedures a day (new customers or customers who want a refit). The wind
tunnel is available 24 hours a day.
CBF offers a free second session should the customer not be entirely satisfied with their
bike fit (internally also known as “rework sessions”). About 2 out of 5 customers come
back for such a “refit,” which takes the same amount of time as the initial fit.
20 minutes of the each fitting procedure is spent on setting up the bike on a stationary
trainer and getting the athlete ready. Almost all of this could happen outside the wind
tunnel, i.e. while another fitting procedure is still going on.
About one day out of 10, the wind tunnel is down for maintenance or repair.
How many new fits are conducted on a typical day when the wind tunnel is in use
(assume the wind tunnel is open that day)?
What is the OEE of the wind tunnel? Recall that the wind tunnel can be used 24h a day.
Tasty Tim’s is a specialty taco restaurant.
The following tasks are required for the successful
assembly of a Tasty taco (times are in seconds per taco):
Chop and trim meat –
Chop vegetables –
Grill meat – 240
Grill vegetables – 180
Final Exam – Module 4 Questions
Please submit your answers via the Module 4 web form on the Coursera site.
50-Step Assembly Line
Consider an assembly line with 50 steps that are carried out sequentially. Each of the 50 steps
has a defect probability of 1%. The final product produced on the assembly line is defective if
any one of the 50 steps made a defect.
At the end of the assembly line there are two operators independently inspecting the product.
Each of them is recognizing a defective product with a 90% probability. Assuming that the
product is not defective, it is moved to the shipping department. Otherwise, the product is
What is the probability that a defective product is produced (independent of the defect
being found or not)?
What is the probability that a defective product is moved to the shipping department?
Process with Scrap
Consider the following four-step assembly operation with quality problems.
The first resource has a processing time of 5 minutes per unit and one employee doing
The second resource has a processing time of 4 minutes per unit. It also has one
employee doing the operation. However, this is a very delicate task and 80% of all
products have to be scrapped after this step.
Two workers are staffed for the third resource. No quality problems occur at this
resource and the processing time is 20 minutes per unit.
At the fourth and final resource, one operator handles the product. No quality problems
exist at this step and the processing time is 12 minutes per unit.
For every unit of demand, how many units have to flow through the second step in the
Where in the process is the bottleneck?