Aside from the satisfaction of over-engineering, as noted by educated_foo above, or from the sheer joy of learning something new for which you've indicated no clear need, if you already "...have a script that extracts..." data, presumably including the 100 ages you want, then why do more than select and sum (cf +=) those ages and obtain your average by dividing by 100 (cf /)?

Alternately, some questions: from what and in what format is the extracted data you're trying to process? How are you doing so now? How would you do it with pencil and paper.

"I don't know much about object-oriented programming" (and that applies to /me too) is a valid statement but that lack of knowledge by itself, lacking one of the motivations in para 1 above, seems (IMO) to suggest that before trying to practice it, you learn enough about its strenths, weaknesses to determine whether the problem you've chosen falls within its generally-agreed-upon 'appropriate uses.'