Practice MC Flashcards
Which term describes the actual time (i.e., including wait time) spent by a customer?
- throughput time
- rush order flow time
- total direct labour content
-direct labour utilization
Throughput time
Which term describes the amount of labour expended on each customer?
- throughput time
- rush order flow time
- total direct labour content
- direct labour utilization
Total direct labour content
Throughput is the same as the system
- cycle time
- rush order flow time
- capacity
- total direct labour content
Capacity
What determines the system-wide cycle time?
- the bottleneck resource
- rush order flow time
- total direct labour content
- direct labour utilization
The bottleneck resource
In general, how does increasing the number of workers in a work area affect the utilization?
Utilization decreases
= total direct labour content/(process cycle time)(# of workers)
Denominator increases, utilization becomes smaller
If the standard deviation of a process decreases, how does the sigma level of a process change?
Increases, bell curve gets skinnier, sigma increases
Which term can be translated as “idiot-proofing” or “mistake-proofing”?
Poka-yoke
Sort
Seiri – eliminate obstacles and unnecessary items
Set In Order
Seiton – arrange items for convenience, clarity, and smooth workflow
Shine
Seiso – keep clean and safe; make problems easy to detect
Standardize
Seiketsu –standardize best practices; make it easy to find things
Sustain
Shitsuke –ensure clarity of standards; audit; promote training and discipline
How does increasing the sample size affect the distance between the LCL and UCL? (Assume R-bar doesn’t change)
Narrows
What do R charts depict?
The range (highest-lowest observation. How the range of the subgroups change over time.
- often used prior to X-chart in order to first see that variability is in control
What do p-charts depict?
Estimate of population percentage (wa), error measured is a frequency/percentage
What do X-bar charts depict?
How the mean or average changes over time
Interarrival times are exponential with a mean of 25 seconds. What is the probability of the next arrival being within 50 seconds?
EXPON.DIST (50,0.04,TRUE)
1/25=0.04 arrival per second (we need a rate)
Interarrival times are exponential with a mean of 25 seconds. What is the probability of 5 or more in the next 50 seconds?
1-POISSON.DIST (4,50*0.04,TRUE)
= 1-POISSON.DIST(4,2,TRUE)
What does the Little’s Law variable Ws represent?
Average time in the system
Ls = λWs
What does the Little’s Law variable Ls represent?
Average # of customers in the system
Ls = λWs
What does the Little’s Law variable λ represent?
Average customer arrival rate
Ls = λWs
If the throughput increases and the average time in the system is constant, what happens to the average number in the system?
Increases
Ls = λWs
If lambda increases, Ws stays the same, then Ls will increase the same amount of lambda (avg customer arrival rate)
Which of the following relationships between how waiting times feel is NOT true?
- occupied time feels longer than unoccupied time
- anxiety makes waits feel longer
- pre-service waits feel longer than in-service waits
- unfair waits feel longer than fair waits
Occupied time feels longer than unoccupied time
