An educated guess is a form of ESTIMATION that is based on knowledge and experience. It is often used when there is not enough information to make an exact calculation. The term 'educated guess' is composed of two words: 'ESTIMATE' (8 letters), which means to make an approximate calculation, and 'THEORY' (6 letters), which refers to a set of principles or ideas that explain a phenomenon. ESTIMATION (10 letters) is the process of making an approximate calculation, while a ballpark figure (14 letters) is an informal ESTIMATE.