3%。 Official website of Jiangsu University Challenge Cup shows that the proportion of grand prize is 3%, and the proportion of first, second and third prizes is 8%, 24% and 65% respectively. Challenge Cup is the abbreviation of "Challenge Cup" national series of scientific and technological academic competitions for college students. It is a national extracurricular academic practice competition for college students co-sponsored by the Central Committee of the Communist Youth League, the China Association for Science and Technology, the Ministry of Education and the National Federation of Students. It is a guiding, demonstrative, practical and mass entrepreneurial exchange activity, which is held every two years.