Do not expect ages given in records to be 100% consistent. There are a variety of reasons why an age can be off in a record. People lie. People guess. People get mixed up. Clerks make mistakes. The individual providing the information guessed. Someone other than the “person being aged” provided the information. The list goes on.
What you are looking for is consistency. Do ages all suggest a year or two of birth (or maybe a slightly larger time frame)? Is there one age that is significantly off from others? Is there one record you think may be less accurate for one reason or another?
Is it possible that the individual in question did not know when they were born–if they were born in a time and place that did not keep records?
Transcribe every document with the age as given. Cite the records clearly and accurately.
For some people, the best you will ever be able to get is an approximate time frame during which they were born.