GOLDIE, C.M., CORNISH, R. and ROBINSON, C.L., 2010. Applying coupon-collecting theory to computer-aided assessments. London Mathematical Society Lecture Note Series, 378, pp. 299-315
Computer-based tests with randomly generated questions allow a large number of different tests to be generated. Given
a fixed number of alternatives for each question, the number of
tests that need to be generated before all possible questions have
appeared is surprisingly low.