Final answer:
The coefficient of variation for the inter-arrival times is 60%.
Step-by-step explanation:
The coefficient of variation (CV) measures the relative variability of a data set compared to its mean. It is calculated by dividing the standard deviation by the mean and multiplying by 100. In this case, the mean inter-arrival time is 5 minutes and the standard deviation is the square root of the variance (9 minutes squared), which is 3 minutes. Therefore, the CV is (3 / 5) * 100 = 60%.