Answer:
Either of ...
Step-by-step explanation:
If we were to say "N increased by 6", we would intend the translation to be "N+6".
When the increase is a fraction, we don't know if that fraction is to be added (N+1/3), or whether that fraction of N is to be added (N+(1/3)N). The statement is ambiguous.
Sometimes the ambiguity is resolved by additional words: "N and 1/3 again as much" means N+(1/3)N. Sometimes, the ambiguity is resolved by context: "the integer N increased by 1/3 is 100" also means N+(1/3)N.
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In my experience, "N increased by 1/3" is most likely intended to be translated as N + (1/3)N. However, the other possibility does exist.
