It means that there is lots of possible answers.
"Vary" means "change".
What does it mean to vary the sentence pattern within a written work?
to work out
Your Mileage May Vary
It mean that the species may get higher or get low.
It means the results may vary depending on what people use in the test, or what the measure it at. Vary means 'might be different'.
Your mileage may vary.
It can vary depending on manufactorer.
"vary" means to take on a different values , to change in value -- pretty much the everyday meaning.
Tattoo meanings will vary from person to person.-Shocker
Perhaps you mean monotone, something which produces sounds which do not vary in pitch.
Standard deviation