Homework Problems

1) A bank's savings account statements contain 24 items of account information. Last month, 2500 bank statements were checked and 52 errors were found in the account items. What is the dpmo value?
a. 0.021
b. 867
c. 0.46

d. 1154

2) A delivery company defines a "defect" as a package delivered later than the promised delivery time. Management wants to monitor the proportion of packages delivered per week beyond the promised delivery time. Management is willing to sample 150 packages per week and determine which of these packages are "defects." Which of the following type of control chart would be most appropriate?
a. -chart
b. R-chart
c. p-chart
d. np-chart

3) Five (5) samples of size three (3) were collected for a variable measurement.All sample data were greater than or equal to 4. The sample means and sample ranges are:

sample number 1 2 3 4 5
sample mean 6.0 4.9 5.0 7.2 4.2
sample range 0.2 0.4 0.1 0.3 0.0
The sample data are identical in which sample?
a. Sample 1
b. Sample 2
c. Sample 3
d. Sample 4
e. Sample 5

4) Twenty (20) samples of size 50 were taken from a process. The total number of defectives found was 86. The standard deviation for the number of nonconforming items for an np-chart is:
a. 0.0396
b. 1.9825
c. 1.2538
d. 2.0736
e. 3.9302

5) The control limits for a c-chart are:
Upper Control Limit = 5.82
Center Line = 1.8
Lower Control Limit = -2.22, or 0.00

Determine the number of samples used to construct this chart.
a. 2
b. 4
c. 10
d. 16
e. Cannot be determined based on the information presented.

6) Nine (9) circuit boards were inspected to determine the total number of defects per unit. The total number of defects found was 144. The standard deviation for use in designing the control limits for the c-chart is:
a. 3
b. 4
c. 12
d. 36
e. none of the above