Honestly, I don't know, but I had to go there.
In "reality" I would place her in her mid to late 20s. Think of the time period, and her relationship with her younger sister (who's probably 22-ish). She's still young and eager enough to be giving it a shot in the big city, but she's not fresh out of high school either.
"Jaws is the Citizen Kane of movies."
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