If it takes a supplier 2 days to deliver an order once it has been placed and the daily
demand for 3 days has been 120, 124, and 125, which of the following is the standard
deviation of usage during lead time?A. About 2.16
B. About 3.06
C. About 4.66
D. About 5.34
E. About 9.30
The standard deviation (Equation 20.6) of daily demand = Square root of (14/3) =
2.1602. This number squared is 4.6667. The square root of 2 days x 4.6667 = the square
root of 9.3333 or 3.055.
You are developing an X-bar chart based on sample means. You know the standard
deviation of the sample means is 4, the desired confidence level is 99 percent, and the
average of the sample means is 20. Which of the following is your LCL?
A. 36
B. 24
C. 9.68
D. 16.79
E. 30.32