Query: In how many languages were students in institutions of higher education being educated in 1974?
Context: It was, by 1961, the third largest producer of petroleum due to new discoveries in the Volga-Urals region and Siberia, trailing only the United States and Saudi Arabia. In 1974, there were 475 institutes of higher education in the republic providing education in 47 languages to some 23,941,000 students. A network of territorially-organized public-health services provided health care.