SAFe Math

Question 1

Little’s Law pertains to queue theory. Can you give the book’s example?

Total items in queue / average processing speed per time period = approximate wait time

Hint: Slide 3.31

Answer 1

Slide 3.31. A new item comes into the backlog with 30 items ahead of it. How long is the wait time?

Total items in queue of 30 / average processing speed of 10 items per quarter = 3 Quarters of processing time before the 31st item is processed.

Question 2

What is a U Curve?

Hint: Slide 3.37

Answer 2

Slide 3.37 Used to determine the optimal batch size by balancing transaction cost and holding cost.

Question 3

How is Total Cost derived?

Hint: Slide 3.37

Answer 3

Slide 3.37. Total Costs
• Sum of holding costs and transactions costs
• Higher transaction costs shift optimum batch size higher
• Higher holding costs shift optimum batch size lower.