In Economical terms, an attainable combination is the set or combination of two goods which is feasible by the economy to manufacture with the available resource allocation and technology.
Unattainable combination is the combination of two goods which is not possible to be produced with allocated resource and available technology.
In a Production Possibility Curve (PPC) that represents the production of two goods, the points that lie on the curve shows the attainable combination (efficient) and those points that lie within the curve also shows attainable combination but it is inefficient production.
Points on the right on outside the curve represents the unattainable combination of goods.
