The question shows that the person who asked it is not very math-savvy, so he didn't know all the details a proper answer would require. Some of the people who answered might've taken this into account and gave a more generic reply that they thought would pragmatically satisfy the purpose (i.e. the asker might not care if it's 47 or 48 years).
But in your answer on the site you gave a very detailed and proper response, you didn't stop at saying 'not enough info'! I think the asker is pleased!