Is butanoic acid more soluble in water than ethyl acetate?
Try to solve the question by analogy. Imagine that you perform a couple of experiments on different glasses of water:


Add vinegar to one glass with water. Does it mix? Yes, it does!
Add olive oil to another glass with water? Does it mix? No, it does not.


Vinegar is a carboxylic acid, whereas olive oil is made of esters. This should suggest to you that carboxylic acids in general are more soluble than esters.

Carboxylic acids, $\ce{R-COOH}$, are acids, that partly dissociate in water

$$\ce{R-COOH + H2O -&gt; H3O+ + R-COO-}$$

to form ions. Supposing that the alkyl chain isn't extremely long, even the undissociated part of the acid added is solvated in water, a polar protic solvent, by hydrogen bonding interactions. In other words, the carboxylic acid is highly soluble in water.

The solubility of ethyl acetate in water is 8.3 g/100 ml (Wikipedia), whereas butanoic acid is completely miscible in water. That is to say, butanoic acid completely dissolves in water, regardless of the proportion of acid to water.