If you get 13 calls in one month which has 31 days is your average call per month is .419?

The numeric value is correct. 13 divided by 31 equals 0.419 (rounded to the nearest thousandth) However the label used is incorrect. Calls divided by days must yield calls per DAY. the closest correct answer is .419 calls per day. To calculate an avergage number of calls per month would typically require a larger sample of months to get a meaningful number. The most you could assert by this sample is the the average calls per month is 13 since you only have one month of data. If the following month, for example you received 23 calls, then the formula would be total number of calls (13 + 23) divided by the number of months (2) which would be 36 divided by 2 or 18 calls per month.