Question: The Boulder County Highway Safety Department monitors speeding tickets issued on the Diagonal Highway between Boulder and Longmont. Speeding tickets issued on the Diagonal have averaged 12 per month.
A) Which type of control chart should be used to monitor speeding tickets at the intersection?
B) What are the upper and lower control limits for this control chart?
C) Last month, 20 speeding tickets were issued on the Diagonal, which seems like a significant increase. Is this sufficient evidence to justify a claim that something has changed on the Diagonal and there are special causes? Explain your answer using the control limits.