A solution of acetone in ethanol shows a positive deviation from Raoult's law because of the miscibility of these two liquids with a difference of polarity and the length of a hydrocarbon chain.
Related Theory
In an ideal solution, the solvent-solute interaction is the same as a solvent-solvent or solute - solute interaction. This implies both the solute and the solvent takes the same amount of energy to escape to the vapour phase as when they are in their pure states.
Caution
Raoult's law is apt for describing ideal solutions. Different liquids that are in the mixture do not have the same uniformity in terms of attractive forces, this type of solutions tends to deviate away from the law.