Dobie works as a window washer, and finds lots of time to think while working. He notices when windows are cracked, and fells that the number of cracked windows has been increasing. He wants to determine if this increase is statistically significant by applying a control chart. He collected data for the past 10 days measuring the number of cracked windows he observed per shift. What is the UCL?
a. 5.90
b. 59.00
c. 13.19
d. 2.42
The LCL?
a. 0
b. 20.14
c. 5.90
d. 2014
Is the number of observed cracked windows within control limits?
a. No
b. Yes
Day Day Day Day Day Day Day Day Day Day
# of cracks 1 2 3 4 5 6 7 8 9 10
3 4 2 4 6 5 8 8 7 12
Dobie noted that the windows he washes may have multiple panes per window. So, rather than counting cracked windows, Dobie instead converts the prior data into cracked window panes. Based on the data below:
Day Day Day Day Day Day Day Day Day Day
# of cracks 1 2 3 4 5 6 7 8 9 10
6 11 4 12 13 12 11 13 7 19
What is the UCL?
a. 13.19
b. 23.66
c. 20.66
d. 10.80
The LCL?
a. 0
b. 10.8
c. 0.94
d. 3.29
Is the number of observed cracked window panes within control limits?
a. Yes
b. No
Is Dobie’s theory that the number of cracked window panes is increasing valid?
a. No
b. Yes