The number of "near misses" recorded for the last 20 months at Lima International Airport is 3, 2, 3, 2, 2, 3, 5, 1, 2, 2, 4, 4, 2, 6, 3, 5, 2, 5, 1, and 3.
Determine the mean number of misses per month and the limits on the number of misses per month.