What is the apple to banana ratio?
What is the apple/banana ratio?
What is the ratio of apples to bananas sold?
A "by volume" comparison means a certain volume of apples compared to the same volume of bananas, eg., "A cubic meter of apples sells for twice the price of a cubic metre of bananas."
(I'm not sure that apples or bananas are sold by volume. It would be more common to use a weight, eg. $x a tonne / a kilogram, or by number)
As far as whether the sentences mean the same, it's complicated.
The relative price of apples and bananas (by any measure) has no bearing on the relative volumes sold (unless you're an economist).
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