I need to find the average age of a group of people, by years and months.
For example if I need the average age of for these birthdays (3/19/90,
2/10/92, 12/3/89 and 1/12/90. I need an result like 17 years and 9 months.
Not just the average year.

I determined the number of days old each person was and then averaged the
days and divided by 365 and came up with 17.98013699. Is 17 yrs 9 months an
accurate interpretation? Is there an easier way to calculate?

Thanks for your help.