query: How long is a general apprenticeship in terms of years?
passage: Apprenticeship
An apprenticeship is a system of training a new generation of practitioners of a trade or profession with on-the-job training and often some accompanying study (classroom work and reading). Apprenticeship also enables practitioners to gain a license to practice in a regulated profession. Most of their training is done while working for an employer who helps the apprentices learn their trade or profession, in exchange for their continued labor for an agreed period after they have achieved measurable competencies. Apprenticeships typically last 3 to 7 years. People who successfully complete an apprenticeship reach the "journeyman" or professional certification level of competence.
passage: United Association
In the first half of the century, the United Association moved to formalize apprenticeship training programs, including making a five-year apprenticeship mandatory in 1921, and in 1938 holding that all apprentices be members of the United Association and attend related training classes. Its National Plumbing Apprenticeship Plan of 1936 was the first set of standards governing apprenticeship to win approval of the federal government.